2D	2-Dimensional
3D	3-Dimensional
3M	Minnesota Mining and Manufacturing
4GL	Fourth Generation Language
4H	Head, Heart, Hands, Health
4WD	Four wheel Drive (see also FWD)
A	Aftermath
AA	Affirmative Action committee
AA	Alcoholics Anonymous
AA	Antiaircraft Artillery
AA	Associate in Accounting
A&A	Astronomy and Astrophysics [Space]
AA	Automobile Association [England]
AAA	American Automobile Association
AAAL	American Academy of Arts and Letters
AAAS	American Association for the Advancement of Science
AAII	American Association of Individual Investors
AAMSI	American Association for Medical Systems Informatics
AAO	Anglo-Australian Observatory [Space]
AAP	Affirmative Action Program
AARC	Anglo-American Cataloging Rules
AARN	Australian Academic Research Network [Networking]
AARP	American Association of Retired Persons
AAS	American Astronomical Society [Space]
AAVSO	American Association of Variable Star Observers [Space]
AB	ABle seaman
ABA	American Bar Association
ABA	American Basketball Association
ABA	American Booksellers Association
ABBR	ABBReviation
ABC	American Broadcasting Company [Corporate name]
AC	Alternating Current (ac, see also DC)
AC	Ante Christum (before Christ)
AC	Ante Cibum (before meals)
ACAA	Agricultural Conservation and Adjustment Administration
ACAWS	Advisory, Caution, And Warning System
ACBL	American Contract Bridge League
ACC	Argonne Code Center
ACCS	Army Command and Control System
ACD	Automatic Call Distributor [Telephony]
ACE	Advanced Composition Explorer [Space]
ACE	Advanced Computing Environments [Corporate name]
ACE	Automatic Calibration and Equalization
ACHEFT	Automated ClearingHouse Electronic Funds Transfer
ACK	ACKnowledge
ACL	Advanced Cmos Logic
ACLU	American Civil Liberties Union
ACM	Association for Computing Machinery
ACRV	Assured Crew Return Vehicle (or) Astronaut Crew Rescue Vehicle [Space]
ACS	Advanced Communications System
ACSE	Association Control Service Entity (ISO/CCITT layer 7)
ACT	Action for Children's Television (in Cambridge, MA)
ACT	American Conservatory Theater
ACTS	Advanced Communications Technology Satellite
ACTS	Automatic Coin Telephone Service [Telephony]
ACU	Alarm Control Unit
ACU	Automatic Call Unit [Telephony]
ACW	Alternating Continuous Waves
AD	After Date
A/D	Analog to Digital converter (see ADC)
AD	Anno Domini (in the year of our Lord)
AD	Application Development
Ad Astra	To the stars [Latin, Space]
ADAP	Alzheimer's disease-associated protein
ADAP	American Discount Auto Parts [Corporate name]
ADB	A DeBugger
ADB	Apple Desktop Bus
ADC	Analog to Digital Converter
ADCI	Automatic Display Call Indicator 
AD&D	Advanced Dungeons & Dragons
ADF	Automatic Direction Finder
ADM	ADMiral
ADP	Adenosine Di-Phosphate
ADP	Administrative Data Processing
ADP	Advanced Data Processing
ADPCM	Pulse Code Modulation with Adaptive Quantization
ADS	Application Development System
ADSR	Attack Decay Sustain Release
ADT	Abstract Data Type
ADT	Atlantic Daylight Time
AE	Application Execution
AEA	American Electronics Association
AEC	Atomic Energy Commission
AEF	American Expeditionary Force (see BEF)
AEGIS	Advanced Electronic Guidance and Instrumentation System
AF	Adventures in Fantasy
AF	Air Force
AF	Audio Frequency
AFADS	Automatic Force Adjustment Data System 
AFATDS	Advanced Field Artillery Tactical Data System
AFB	Air Force Base
AFC	American Football Conference
AFC	Automatic Flight Control
AFC	Automatic Frequency Control
AFCAC	Air Force Computer Acquisition Center
AFCC	Air Force Communications Command
AFGE	American Federation of Government Employees
AFIPS	American Federation of Information Processing Societies
AFL	American Federation of Labor
AFL	American Football League
AFLCIO	American Federation of Labor and Congress of Industrial Organizations
AFNOR	Association Francaise de NORmalization
AFP	Appletalk Filing Protocol
AFS	Andrew File System
AFSC	Air Force Systems Command
AFSCME	American Federation of State, County and Municipal Employees
AFTRA	American Federation of Television and Radio Artists
AG	Adjutant General
AG	Arcade Game
AG	Attorney General
AGCT	Army General Classification Test
AGN	Active Galactic Nucleus [Space]
AHL	American Hockey League
AHQ	Air HeadQuarters
AI	Artificial Intelligence
AIAA	American Institute of Aeronautics and Astronautics [Space]
AIC	Automatic Intercept Center 
AID	Agency for International Development
AIDDE	Ames' Interactive Dynamic Display Editor
AIDS	Acquired ImmunoDeficiency Syndrome
AIOD	Automatic Identification Outward Dialing 
AIS	Automatic Intercept System
AIX	Advanced Interactive eXecutive (IBM's name for UNIX)
AJ	Astronomical Journal [Space]
AK	Alaska
AKA	Also Known As
AL	Alabama [US state postal designation]
AL	American League (baseball)
ALA	American Library Association
ALA	Automobile Legal Association
ALBM	Air-to-Land Ballistic Missile
ALC	Automatic Load Control
ALGOL	ALGOrithmic Language
ALIT	Automatic Line Insulation Testing [Telephony]
ALPO	Association of Lunar and Planetary Observers [Space]
ALS	Advanced Launch System [Space]
ALU	Arithmetic Logic Unit
A&M	Agricultural and Mechanical
AM	Amplitude Modulation
AM	Ante Meridiem (before noon)
AMA	American Medical Association
AMA	Automatic Message Accounting [Telephony]
AMARC	Automatic Message Accounting Recording Center 
AMBA	Association of Master of Business Administration
AMC	Albany Medical College
AMC	American Motors Corporation(?) [Corporate name]
AMC	Appalachian Mountain Club
AMD	Advanced Micro Devices [Corporate name]
AMEX	AMerican EXpress [Corporate name]
AMI	Alternate Mark Inversion (see also NRZ, NRZI, B8ZS)
AMORC	Ancient Mystic Order Rosae Crucis
AMP	Adenosine MonoPhosphate
AMPAS	Academy of Motion Picture Arts and Sciences
AMPAS	Acedemy of Motion Picture Arts and Sciences
AMRAAM	Advanced Medium Range Air-To-Air Missile
AMROC	American Rocket Company [Space]
AMSAT	radio AMateur SATellite corp.
AMU	Atomic Mass Unit
AMVET	AMerican VETeran
ANA	American Nurses Association
ANAC	Automatic Number Announcemnt Circuit [Telephony]
ANC	All Number Calling [Telephony]
ANC	Army Nurse Corps
ANDF	Architecture-Neural Distribution Format
ANF	Automatic Number Forwarding [Telephony]
ANG	Air National Guard
ANI	Automatic Number Identification (see also: CLID) [Telephony]
ANL	Argonne National Laboratory
ANOVA	ANalysis Of VAriance
ANPA	American Newspaper Publishers Association
ANSI	American National Standards Institute
ANZUS	Australia, New Zealand, United States
AO	Account Of
AOA	Abort Once Around [NASA, Shuttle]
AOA	Abort Once Around (Shuttle abort plan) [Space]
AOL	Absent Over Leave (see AWOL)
AOS	Academic Operating System
AOS	Alternate Operator Service [Telephony]
A/P	Accounts Payable
AP	Additional Premium
AP	All Points
AP	Associated Press [Corporate name]
APA	All Points Addressable
APA	American Psychological Association
APB	All Points Bulletin
APDA	Apple Programmers and Developers Association
API	Application Programming Interface
APICS	American Production and Inventory Control Society
Ap.J	Astrophysical Journal [Space]
APL	A Programming Language
APL	acute promyelocytic leukemia [Disease]
APO	Alpha Phi Omega, service fraternity
APO	Army Post Office
APP	Applications Portability Profile
APPC	Advanced Peer-to-Peer Communications
APR	Annual Percentage Rate (as in loan interest)
APSE	Ada Programming Support Environment
APU	Auxiliary Power Unit [Space]
AQ	Accumulator-Quotient register
A/R	Accounts Receivable
AR	Address Register
AR	Arkansas
ARC	AIDS-related complex
ARC	American Red Cross
ARC	Ames Research Center (NASA) [Space]
ARCNET	Attached Resource Computer local area NETwork
ARO	After Receipt of Order
ARP	Address Resolution Protocol
ARPA	Advanced Research Projects Agency (of the DoD, see DARPA)
ARPANET ARPA (q.v.) NETwork
ARRL	Amateur Radio Relay League
ARV	American Revised Version
AS	Anglo-Saxon
ASA	Acetyl Salicylic Acid
ASAP	As Soon As Possible
ASC	Accredited Standards Committee
ASCAP	American Society of Composers, Authors, and Publishers
ASCC	Automatic Sequence-Controlled Calculator
ASCII	American Standard Code for Information Interchange
ASDIC	Anti-Submarine Detection Investigation Committee (British for sonar)
ASDSP	Application-Specific Digital Signal Processor
ASG	Automated Sciences Group
ASHRAE	Amer. Soc. of Heating, Refrigerating and Air-cond. Engineers, inc.
ASIC	Application Specific Integrated Circuit
ASME	American Society of Mechanical Engineers
ASN	Abstract Syntax Notation One (ISO/CCITT ASN.1)
ASP	Aggregated Switch Procurement
ASRM	Advanced Solid Rocket Motor [Space]
ASSR	Autonomous Soviet Socialist Republic
AST	Atlantic Standard Time
ASV	American Standard Version
AT	Atlantic Time
ATA	Automatic Trouble Analysis 
ATACC	Advanced Tactical Air Command Central
ATB	Advanced Technology Bomber (stealth bomber)
ATC	Air Traffic Control
ATDRS	Advanced Tracking and Data Relay Satellite [Space]
ATF	Advanced Technology Fighter
ATIS	Atherton Tools Interface Specification
ATLAS	Atmospheric Laboratory for Applications and Science [Space]
ATM	Amateur Telescope Maker [Space]
ATM	Asynchronous Transfer Mode
ATM	Automatic Teller Machine
ATO	Abort To Orbit [NASA, Shuttle]
ATO	Abort To Orbit (Shuttle abort plan) [Space]
ATOMS	AT&t Optimized Materials Simulator
ATP	Adenosine TriPhosphate
ATPCO	Airline Tariff Publishing COmpany
AT&T	American Telephone & Telegraph [Corporate name]
ATT	American Telephone & Telegraph (normally written AT&T when seperate)
ATTIS	American Telephone and Telegraph Information Systems [AT&T] (Division)
ATV	All Terrain Vehicle
AU	Astronomical Unit (93,000,000 miles) [Space]
AU	Astronomical Unit [Space]
AUI	Attachment Universal Interface
AURA	Association of Universities for Research in Astronomy [Space]
AUS	Army of the United States
AUTODIN AUTOmatic DIgital Network
AUTOVON AUTOmatic VOice Network
AV	AudioVisual
AVLIS	Atomic Vapor Laser Isotope Separation
AWACS	Airborne Warnings And Control Systems
AWEA	American Wind Energy Association
AWK	al Aho, peter Weinberger, brian Kernighan (pattern scanning language)
AWOL	Absent WithOut Leave (also Absent Without Official Leave) (see AOL)
AW&ST	Aviation Week and Space Technology (a.k.a. AvLeak) [Space]
AXAF	Advanced X-ray Astrophysics Facility [Space]
AZ	Arizona
B	Book
B8ZS	Binary 8 Zero Substitution (see also NRZ, NRZI, AMI)
BA	Bachelor of Arts
BACH	Business Alliance for Commerce in Hemp
BAFO	Best And Final Offer
BARRNet Bay Area Regional Research Network (SF Bay Area)
BASIC	Beginner's All-purpose Symbolic Instruction Code
BATSE	Burst And Transient Source Experiment (on GRO) [Space]
BB	Bases on Balls
BB	Best of Breed
BB	Bunnies and Burrows
BBA	Bachelor of Business Administration
BBB	Better Business Bureau
BBC	British Broadcasting Corporation
BBL	Barrel
BBN	Bolt, Beranek, and Newman, Inc. [Corporate name]
BBXRT	Broad-Band X-Ray Telescope (ASTRO package) [Space]
BC	Battlecars
BC	Before Christ
BC	British Columbia
BC/BS	Blue Cross/Blue Shield
BCD	Bad Conduct Discharge
BCD	Binary Coded Decimal
BCDIC	Binary Coded Decimal Interchange Code
BCE	Before the Common Era (substitute for BC)
BCNU	Be Seeing You [Net jargon]
BCP	Byte Controlled Protocols
BCPL	Basic Combined Programming Language
BCS	Bachelor of Commercial Science
BCS	Binary Compatibility Standard
BCS	Boston Computer Society
BCS	British Computer Society
BD	Bachelor of Divinity
BD	Bank Draft
BD	Bills Discounted
BD&D	Basic Dungeons & Dragons
BDF	Binary Distribution Format
BDT	Billing Data Transmitter
BE	Bill of Exchange
BEF	British Expeditionary Force (see AEF)
BELCORE BELL COmmunications REsearch
BEM	Bug Eyed Monster
BEM	Bug-Eyed Monster [Space]
BENELUX BElgium, NEtherlands, and LUXembourg
BER	Bit Error Rate
BERT	Bit Error Rate Test
BEST	Borland Enhanced Support and Training
BF	Brought Forward
BFA	Bachelor of Fine Arts
BFD	Bristol (RI) Fire Department (probably typical of any town starting "B")
BH	Black Hole [Space]
BH	Boot Hill
BHP	Brake HorsePower
BICS	Building Industry Consulting Services [Telephony]
BID	Bis In Die (twice a day)
BIMA	Berkeley Illinois Maryland Array [Space]
BIOS	Basic Input Output System
BIS	Business Information System
BISDN	Broadband ISDN (q.v.) [Telephony]
BiSync	Binary Synchronous Communications (BSC is preferred) [IBM]
Bit	BInary digiT
BITNET	Because It's Time Network
BLAST	BLocked ASynchronous Transmission
BLERT	BLock Error Rate Test
BLF	Busy Lamp Field [Telephony]
BLT	Bacon, Lettuce, and Tomato (sandwich)
BLT	BLock Transfer [Instruction]
BLT	Branch Less Than [Instruction]
BM	Basal Metabolism
BM	Bowel Movement
BMA	Bank Marketing Association
BMEWS	Ballistic Missile Early Warning
BMO	Ballistic Missile Office
BMOC	Big Man On Campus
BMR	Basal Metabolism Rate
BNC	Bayonet Neill Concelman (connector) [Electronics] (see also TNC)
BNF	Bachus-Naur Form
BO	Body Odor
BO	Branch Office
BO	Buyer's Option
BOC	Bell Operating Company
BOD	Board Of Directors
BOF	Birds Of a Feather
BOM	Bill Of Materials
BOOTP	Bootstrap Protocol [Internet]
BOQ	Bachelor Officers' Quarters
BOS	Business Office Supervisor
BOSIX	Biin Open System Interface eXtension
BP	Blood Pressure
BP	British Petroleum
BP	British Pharmacopoeia
BPI	Bits Per Inch
BPL	Boston Public Library
BPL	Branch if PLus [Instruction]
BPOE	Benevolent and Protective Order of Elks
BPS	Bits Per Second
BR	Bills Receivable
BR	British Rail
BRA	Boston Redevelopment Authority
BRI	Basic Rate Interface (ISDN) [Telephony]
BRIEF	Basic Reconfigurable Interactive Editing Facility
BRL	army Ballistic Research Laboratory
BRS	Bibliographic Retrieval Service
BS	Bachelor of Science
BS	Bill of Sale
BSA	Birmingham Small Arms
BSA	Boy Scouts of America
BSc	Bachelor of SCience
BSC	Binary Synchronous Communications (also sometimes BiSync) [IBM]
BSD	Berkeley Software Distribution
BSN	Bachelor of Science in Nursing
BSS	Block Started by Symbol
BSTJ	Bell System Technical Journal
BT	British Telecom
BTAM	Basic Telecommunications Access Method [IBM]
BThU	British Thermal Unit (BTU {q.v.} is preferred)
BTL	Bell Telephone Laboratories
BTO	Bachman Turner Overdrive
BTU	British Thermal Unit
BTW	By The Way [Net jargon]
BU	Boston University
BUF	B-52 bomber ("Big Ugly Fellow") [USAF]
BV	Blessed Virgin
BWI	Baltimore-Washington International (airport)
BWI	British West Indies
BX	Base eXchange (see also PX)
c	centi- (metric 1/100)
C	programming language (successor to B, which was based on BCPL)
CA	California
CA	Chartered Accountant
CA	Chief Accountant
CA	Chronological Age
CA	Collision Avoidance (as in CSMA/CA (q.v.))
CAB	Civil Aeronautics Board
CACM	Communications of the Association for Computing Machinery
CAD	Computer Aided Design (sometimes seen as CAD/CAM)
CAD	Computer Aided Dispatching
CAE	Common Applications Environment
CAE	Computer Aided Engineering
CAI	Computer Aided Instruction
CAIS	Common Apse Interface Specification
CALS	Computer-aided Acquisition and Logistics Support
CAM	Computer Aided Management
CAM	Computer Aided Manufacturing (sometimes seen as CAD/CAM)
CAM	Content Addressable Memory
CAMA	Centralized Automatic Message Accounting [Telephony]
CAMP	Campaign Against Marijuana Planting
CAP	Civil Air Patrol
CAP	Columbia Appletalk Package
CAR	Contents of the Address part of the Register (LISP)
CARE	Committee on American Relief in Europe
CARP	California Air Resources Board
CASE	Computer Aided Software Engineering
CASSIS	Classification and Search Support Information System
CAT	Computer-Aided Tomography
CATIS	Common Applications and Tools Integration Services
CATV	Common Antenna TeleVision
CATV	Community Antenna TeleVision
CAVU	Ceiling And Visibility Unlimited
CB	Citizens Band radio
CBC	Canadian Broadcasting Corporation
CBD	Cash Before Delivery
CBD	Commerce Business Daily
CBEMA	Computer & Business Equipment Manufacturers Association
CBR	Chemical, Biological, Radiological warfare
CBS	Columbia Broadcasting System [Corporate name]
CBW	Chemical and Biological Warfare
CC	C (language) Compiler
CC	Carbon Copy
CCA	Computer Corporation of America [Corporate name]
CCAFS	Cape Canaveral Air Force Station [Space]
CCC	Canadian Committee on Cataloging
CCC	Civil(ian) Conservation Corps
CCC	Command, Control, and Communications (sometimes C^3)
CCC	Concourse Computer Center [MIT]
CCCCM	CCC CounterMeasures (sometimes C^3CM)
CCCI	Command, Control, Communications, and Intelligence
CCD	Charge Coupled Device (see CID)
CCD	Charge-Coupled Device [Space]
CCDS	Centers for the Commercial Development of Space [Space]
CCF	Hundred Cubic Feet
CCI	Computer Carrier Interrupt
CCI	Computer Consoles, Incorporated
CCIP	Continuously Computed Impact Point
CCIRN	Coordinating Committee for Intercontinental Research Networking
CCIS	Common Channel Interoffice Signaling [Telephony]
CCITT	Comite' Consultatif International Telegraphique et Telephonique
CCITT	Consultative Committee on International Telephony and Telegraphy
CCITT	International Telegraph and Telephone Consultative Committee
CCR	Commitment, Concurrency, and Recovery
CCR	Creedence Clearwater Revival [Music]
CCRI	Community College of Rhode Island [Corporate name]
CCRP	Continuously Computed Release Point
CCS	Hundred Call Seconds [Telephony]
CCS7	Common Channel Signalling (version #7) [Telephony, AT&T]
CCSA	Common Control Switching Arrangement [Telephony]
CCTA	Central Computer and Telecommunications Agency
CCTV	Closed Circuit TeleVision
CD	Carrier Detect (properly DCD (q.v.)) (EIA RS-232-C)
CD	Certificate of Deposit
CD	Civil Defense
CD	Collision Detection (as in CSMA/CD (q.v.))
CD	Compact Disk
CDA	Call Data Accumulator
CDA	Compound Documents Architecture
CDC	Centers for Disease Control
CDC	Control Data Corporation, Inc. [Corporate name]
CDEV	Control panel DEVice
CDIAC	Carbon Dioxide Information Analysis Center
CDO	Community Dial Office
CDR	CommanDeR
CDR	Contents of the Decrement part of the Register (LISP)
CD-ROM	Compact Disk Read Only Memory
CD-ROM	Compact Disk Read-Only Memory [Space]
CDSF	Commercially Developed Space Facility
CDT	Central Daylight Time
CDU	Control Display Unit
CE	Chemical Engineer
CE	Civil Engineer
CE	Common Era (substitute for AD)
CE	Corps of Engineers
CE	Customer Engineer (see also FE, SE)
CEA	Commissariat a l'Energie Atomique (Frenc Atomic Energy Commision)
CEA	Council of Economic Advisors
CEA	County Education Authority
CEC	Commission of the European Communities
CED	Committee for Economic Development
CELSS	Controlled Ecological Life Support System [Space]
CENS	Centre d'Etudes Nucleaires de Seclay
CENTO	CENtral Treaty Organization
CEO	Chief Executive Officer
CERFnet California Education and Research Federation Network
CERN	European Organization for Nuclear Research
CERN	organisation (formerly Conseil) Europeenne pour la Recherche Nucleaires
CERT	Computer Emergency Response Team
CEVI	Common Equipment Voltage Indicator
CF	Carry Forward
CF	Coin First (payphone) [Telephony]
CF	Cystic Fibrosis [Disease]
CFA	Center For Astrophysics [Space]
CFC	Chloro-FluoroCarbon [Chemical]
CFC	Combined Federal Campaign
CFD	Computational Fluid Dynamics
CFHT	Canada-France-Hawaii Telescope [Space]
CFI	Cost, Freight, and Insurance
CFL	Canadian Football League
CFO	Chief Financial Officer
CG	Coast Guard
CG	Commanding General
CGA	Color Graphics Adapter
CGCT	Compagnie Generale de Constructions Telephoniques
CG&E	Cincinnati Gas & Electric
CGE	Compagnie Generale d'Electricite
CH	Cardboard Heroes
CH	ClearingHouse
CH	CourtHouse
CH	Customs House
CHA	Champions
CHAP	CHAnnel Processor
CHARA	Center for High Angular Resolution Astronomy [Space]
CHI	Chill:	Adventures into the Unknown
CHOTS	Corporate Headquarters Office Technology System
CHP	California Highway Patrol
CI	Cubic Inches
CIA	Central Intelligence Agency [US Government]
CIA	Culinary Institute of America (Hyde Park, NY)
CIC	Carrier Identification Codes [Telephony] (10XXX codes)
CIC	Committee on Institutional Cooperation
CIC	Coordination and Information Center [CSNet]
CICA	Competition in Contracting Act
CICS	Customer Information Control System [IBM]
CID	Caller ID [Telephony] (see also: CLID, ANI)
CID	Central Institute for the Deaf
CID	Charge Injection Device (see CCD)
CID	Computer Integrated Design
CIDIN	Common Icao Data Interchange Network
CIM	Computer Integrated Manufacturing
CIO	Chief Information Officer
CIRRIS	Cryogenic InfraRed Radiance Instrument for Shuttle [Space]
CISC	Complex Instruction Set Computer
Cislunar	The space between the Earth and the Moon
CIT	California Institute of Technology
CIT	Case Institute of Technology (part of CWRU, Cleveland, OH)
CIT	Circumstellar Imaging Telescope [Space]
CLASP	Comprehensive Logistics Automated Support Program
CLASS	Custom Local Area Signaling Service [Telephony]
CLI	Command Line Interpreter
CLID	Calling Line ID [Telephony] (see also: CID, ANI)
CLNP	Connectionless-mode Network Protocol
CLNS	Connectionless-mode Network Service
CLR	Combined Line and Recording
CLRC	Circuit Layout Record Card
CLU	Chartered Life Underwriter
CLUT	Color LookUp Table
cm	centimeters
CM	Command Module (Apollo spacecraft) [Space]
CM	Congregation of the Mission
CMC	Communication Machinery Corp.
CMD	Centralized Message Distribution
CMIP	Common Management Information Protocol
CMIS	Common Management Information Services
CML	Current Model Logic
CMMU	Cache/Memory Management Unit
CMOS	Complementary Metal Oxide Semiconductor (see MOS)
CMOT	Common Management Information Services and Protocol Over TCP/IP
CMRR	Common Mode Rejection Ratio
CMS	Circuit Maintenance System
CMSgt	Chief Master Sergeant
CMU	Carnegie-Mellon University
CMYK	Cyan, Magenta, Yellow, blacK
CN	Canadian National [Corporate name, Railroading]
CN/A	Customer Name / Address [Telephony]
CNI	Common Network Interface [Telephony, AT&T] (Department of AT&T)
CNN	Cable News Network
CNO	Carbon-Nitrogen-Oxygen [Space]
CNO	Chief of Naval Operations
CNR	Canadian National Railways
CNR	Carrier to Noise Ratio
CNRI	Corporation for National Research Initiatives
CNRS	Centre National de la Recherche Scientifique (French National Center for Scientific Research)
CNS	Central Nervous System
CNSR	Comet Nucleus Sample Return [Space]
CO	Cash Order
CO	Central Office [Telephony]
CO	Colorado
CO	Commanding Officer
CO	Conscientious Objector
C/O	in Care Of
COB	Close Of Business
COBE	COsmic Background Explorer [Space]
COBOL	COmmon Business Oriented Language
COC	Call of Cthulhu
COCOT	Customer Owned, Coin Operated Telephone [Telephony]
COD	Collect On Delivery; Cash On Delivery
CODEC	COder-DECoder
COER	Central Office Equipment Report
COLA	Cost-Of-Living Allowance
COM	Computer Output (on) Microfiche
COM	Computer Output (on) Microfilm
COMAS	Central Office Maintenance and Administration System
COMM	Communications
COMPACT COMmercial Product ACquisition Team
COMPTEL COMPton TELescope (on GRO) [Space]
COMSAT	Communications Satellite [Space]
CONACYT Consejo Nacional de Cienca Y Tecnologia (Mexican National Council of Science and Technology)
CONS	Connection-Oriented Networking Service
CONS	Connection-Oriented Networking Session
CONS	CONStruct (LISP)
CORE	COntrolled Requirement Expression
CORN	COmputer Resource Nucleus
COS	Corporation for Open Systems
COSINE	Cooperation for Open Systems Interconnection Networking in Europe
COSMIC	COmmon System Main InterConnecting frame
COSMIC	COmputer Software Management and Information Center
COSMOS	COmputer System for Mainframe OperationS
COSTAR	Corrective Optics Space Telescope Axial Replacement [Space]
COT	Card Or Tape (NCR)
CP	Campus Police (MIT, others probably too)
CP	Canadian Pacific
CP	Chemically Pure
CP	Command Post
CP	Command Processor
CP	CoPy
CP	the Canadian Press
CPA	Certified Public Accountant
CPE	Customer Premises Equipment
CPE	Customer Provided Equipment
CPFF	Cost Plus Fixed Fee
CPI	Characters Per Inch
CPI	Common Programming Interface
CPL	Combined Programming Language
CPM	Control Program for Microcomputers (sometimes CP/M)
CPM	Control Program Monitor (sometimes CP/M)
CPO	Chief Petty Officer
CPO	Chief Post Office
CPR	Canadian Pacific Railway
CPS	Characters Per Second
CPSR	Computer Professionals for Social Responsibility
CPT	CaPTain
CPU	Central Processing Unit
CPW	Certified Public Weigher
CQ	Change of Quarters
CR	Carriage Return (ASCII 15 octal)
CRA	Cambridge Redevelopment Authority
CRAF	Comet Rendezvous / Asteroid Flyby [Space]
CRAM	Card Random Access Memory (NCR, but maybe others)
CRC	Chemical Rubber Company
CRC	Cyclic Redundancy Check
CREG	Concentrated Range Extension with Gain
CREN	The Corporation for Research and Educational Networking (merge of BITNET and CSNet)
CRRES	Combined Release / Radiation Effects Satellite [Space]
CRRES	Combined Release and Radiation Effects Satellite [NASA]
CRT	Cathode Ray Tube (also generic reference to a terminal)
CRTC	Canadian Radio-television and Telecommunications Commission
C&S	Chivalry & Sorcery
CS	Civil Servant
CS	Computer Science; Computing Science
CS	County Seat
CSA	Confederate States of America
CSAB	Computing Sciences Accreditation Board
CSACS	Centralized Status, Alarm and Control System
CSC	Computer Sciences Corporation
CSDC	Circuit Switched Digital Capability
CSF	Critical Success Factor
CSI	Commercial Systems Integration
CSIS	Canadian Security and Intelligence Service
CSL	Coin Supervising Link 
CSM	Command and Service Module (Apollo spacecraft) [Space]
CSM	Command Sergeant Major
CSMA	Carrier Sense Multiple Access
CSMA/CA Carrier Sense Multiple Access with Collision Avoidance
CSMA/CD Carrier Sense Multiple Access with Collision Detection
CSNET	Computer + Science Network (merged with BITNET to make CREN)
CSO	Central Services Organization
CSOC	Consolidated Space Operations Center (at Colorado Springs)
CSP	Control Switching Point
CSR	Control and Status Register
CSR	Customer Service Representative [Telephony]
CSRG	Computer Systems Research Group
CSRS	civil Service Retirement System
CSS	Customer Switching System
CST	Central Standard Time
CSU	Channel Service Unit
CT	Central Time
C&T	Communications & Tracking [Space]
CT	Connecticut
CTC	Canadian Transport Commission
CTC	Centralized Traffic Control [Railroading]
CTD	Computing and Telecommunications Division
CTIO	Cerro Tololo Inter-american Observatory
CTIO	Cerro Tololo Interamerican Observatory [Space]
CTNE	Compania Telefonica Nacional de Espana
CTS	Clear To Send (EIA RS-232-C)
CTS	Compatible Timesharing System
CTV	Canadian TeleVision network
CU	Close-Up
CUA	Common User Access
CUL	See You Later [Net jargon]
CV	Curriculum Vitae
CW	Car Wars
CW	Chemical Warfare
CW	Child Welfare
CW	Churchwarden
CW	Churdwarden
CW	Continuous Wave
CWO	Cash With Order
CWO	Chief Warrant Officer
CWRU	Case Western Reserve University
CXI	Common X-windows Interface
CY	Calendar Year
CYO	Catholic Youth Organization
CZ	Canal Zone
D	Depth
DA	Days after Acceptance
DA	Department of Agriculture
DA	Deposit Account
D/A	Digital to Analog converter
DA	Directory Assistance (/C = computerized, /M = Microfilm) [Telephony]
DA	District Attorney
DA	Don't Answer [Telephony] (may be more general)
DAC	Digital to Analog Converter
DA/C	Directory Assistance/Computerized
DACCS	Digital Access Cross Connect System [Telephony] (suspect, see DACS)
DACS	Digital Access Cross-connect System [Telephony]
DAD	Draft ADdendum
DAG	Directed Acyclic Graph
DAL	Dedicated Access Line [Telephony]
DA/M	Directory Assistance/Microfilm
DAP	Division Advisory Panel (of NSF (q.v.) DNCRI (q.v.))
DAR	Daughters of the American Revolution
DARE	Drug Abuse Resistance Education
DARPA	Defense Advanced Research Projects Agency (of the DoD, see also ARPA)
DASD	Direct Access Storage Device
DAT	Digital Audio Tape
DATA	Defense Air Transport Administration
DAV	Disabled American Veterans
DB	DataBase
db	decibel(s)
dba	doing business as
DBF	DBase Format
DBME	DataBase Managment Environment
dbms	DataBase Management System (rdbms for Relational ...)
DBRAD	Data Base Relational Application Directory
DC	Direct Current (dc, see also AC)
DC	District of Columbia
DCA	Defense Communications Agency
DCA	Distributed Communication Architecture
DCA	Document Content Architecture
DCC	Descriptive Cataloging Committee
DCCO	Defense Commercial Communications Office
DCD	Data Carrier Detect (sometimes CD (q.v.)) (EIA RS-232-C)
DCE	Data Communication Equipment
DCL	Digital Command Language
DCP	Distributed Communications Processor
DCTS	Dimension Custom Telephone Service
DD	Daredevils
DD	Data Dictionary
DD	Days after Date
DD	Demand Draft
DD	Dishonorable Discharge
DD	Disk Drive
DD	Doctor of Divinity
D&D	Dungeons & Dragons
DDC	Digital Data Converter
DDCU	DC-to-DC Converter Unit [Space]
DDD	Direct Distance Dialing [Telephony] (principally US, elsewhere STD)
DDL	Document Description Language
DDN	Defense Data Network
DDP	Distributed Data Processing
DDS	Dataphone Digital Service [AT&T]
DDS	Digital Data Service
DDS	Direct Digital Service
DDS	Doctor of Dental Science
DDS	Doctor of Dental Surgery
DDT	DEC Debugging Tape
DDT	Di-<something> (pesticide)
DDT	Dynamic Debugging Technique
DE	Delaware
DEA	Drug Enforcement Agency [US Government]
DEAR	Department of Energy Acquisition Regulation
DEC	Digital Equipment Corporation [Corporate name]
DECUS	Digital Equipment Corporation Users Society
DES	Data Encryption Standard [NIST]
DEW	Distant Early Warning (as in DEW Line)
DF	Damage Free
D/F	Direction Finding
DFC	Distinguished Flying Cross
DFD	Data Flow Diagram
DFE	Data Flow Editor
DFM	Distinguished Flying Medal
DFN	Deutsche Forschungsnetz Verein (German Research Network Association)
DFRF	Dryden Flight Research Facility [Space]
DFS	Depth-First Search
DFW	Dallas-Ft.Worth (regional airport)
DG	Data General [Corporate name]
DG	Dei Gratia (by the grace of God)
DG	Director General
DGSC	Defense General Supply Center
DHHS	Department of Health and Human Services
DHSS	british Department of Health and Social Security
DHSS	Department of Health and Social Security (British)
DIA	Document Interchange Architecture
DIAD	(magnetic) Drum Information Assembler / Dispatcher
DIAL	Direct Information Access Line
DIAS	Defense Automatic Integrated System
DID	Direct Inward Dialing [Telephony]
DIF	Document Interchange Format
DIN	Deutsches Institut fur Normung
DIRE	Dire Is Really Emacs
DIS	Draft International Standard [ISO]
DISA	Data Interchange Standards Association
DISOSS	Distributed Office Support System [IBM]
DIY	Do It Yourself
DJ	Disc Jockey
DLA	Defense Logistics Agency
DLI	Data Link Interface(?)
DLL	Data Link Layer [ISO OSI]
DLL	Dial Long Line equipment
DLO	Dead Letter Office
DM	Dungeon Master
DMA	Direct Memory Access
DMD	Doctor of Dental Medicine
DME	Distance Measuring Equipment
DMF	Probably part of an X.400 address in Europe
DMOS	Diffusion Metal Oxide Semiconductor (see MOS)
DMSP	Defense Meteorological Satellite Program [Space]
DMV	Department of Motor Vehicles
DMV	Department of Motor Vehicles (Calif)
DMZ	DeMilitarized Zone
DNA	DeoxyriboNucleic Acid
DNA	Digital Network Architecture [DEC]
DNCRI	[NSF] (q.v.) Division of Networking and Communications Research and Infrastructure
DNHR	Dynamic NonHierarchical Routing
DNIC	Data Network Identification Code [Telephony]
DNIS	Dialed Number Identification Service (see also DID) [Telephony]
DNL	Director of Naval Laboratories
DNR	Dialed Number Recorder [Telephony]
DNS	Domain Name System
DOA	Dead On Arrival
DOB	Date Of Birth
DOC	Dynamic Overload Control
DOD	Department Of Defense [US Government] (sometimes DoD)
DOE	Department of Energy [US Government]
DOHC	Dual OverHead Cams [Automotive]
DOMAIN	Distributed Operating Multi Access Interactive Network (Apollo)
DOS	Disk Operating System
DOT	Department Of Transportation [US Government]
DOT&E	Director, Operational Test and Evaluation
DOV	Data Over Voice [Telephony]
DOY	Day of Year
DP	Data Processing
DP	Dial Pulse [Telephony]
DP	Displaced Persons (expelled from native land)
DP	Display Postscript
DP	Double Penetration
DP	Double Play
DP	Draft Proposal
DPA	Delegation of Procurement Authority
DPANS	Draft Proposed American National Standard
DPI	Dots Per Inch
DPS	Display PostScript
DQ	Dairy Queen
DQ	Dragon Quest
DQDB	Distributed Queue Dual Bus (IEEE 802.6) [Telephony, Networking]
DQL	Database Query Language
DR	Dead Reckoning
DR	Dining Room
DRAM	Dynamic Random Access Memory (as opposed to static RAM)
DRD	Data Reading Device
DRE	Directional Reservation Equipment
DRG	Democratic Republic of Germany (East Germany)
DRI	Defense Research Internet
DRI	Digital Research, Incorporated [Corporate name]
d.s.	died single [Genealogy]
DS	Double-Sided
DS	Draft Standard
DSA	Dial System Assistance
DSE	Data Structure Editor
DSEE	Domain Software Engineering Environment
DSM	Distinguished Service Medal
DSO	Distinguished Service Order
DSP	Decessit Sine Prole (died without issue)
DSP	Digital Signal Processing
DSRI	Digital Standard Relational Interface
DSS	Decision Support System
DSS	Direct Station Selection [Telephony]
DST	Daylight Saving Time
DSTN	Double SuperTwisted Nematic
DSU	Digital Service Unit
DT	Delirium Tremens
DTE	Data Terminal Equipment
DTF	Dial Tone First payphone [Telephony]
DTMF	Dial Tone Multi Frequency [Telephony]
DTP	DeskTop Publishing
DTR	Data Terminal Ready (EIA RS-232-C)
DUI	Driving Under the Influence
DUT	Device Under Test
DV	Deo Vo lente (God willing)
DVM	Digital Volt Meter
DVM	Doctor of Veterinary Medicine
DWAPS	Defense Warehousing Automated Processing System
DWI	Died Without Issue [Genealogy]
DWI	Driving While Intoxicated
DWIM	Do What I Mean
DX	Distance (as in long distance radio communication)
DXT	Data eXtractT facility
d.y.	died young [Genealogy]
E	East
E	Espionage
EADASS	Engineering and Administrative Data AcquiSition System
EAFB	Edwards Air Force Base [Space]
EAN	Certainly part of an X.400 Address in Europe
EARN	European Academic Research Network
EAS	Extended Area Service (or Engineering Admin. System) 
EASI	European Academic Supercomputer Initiative (of IBM)
EBCDIC	Extended Binary Coded Decimal Interchange Code
EC	Exchange Carrier [Telephony]
ECAFE	Economic Commission for Africa and the Far East
ECASS	Electronically Controlled Automatic Switching System
ECASS	Export Control Automated Support System
ECC	Error Correction Code
ECC	Error Correction Code (corrects error in memory or transmission)
ECCM	Electronic Counter-CounterMeasures
ECDO	Electronic Community Dial Office
ECG	ElectroCardioGram
ECL	Emitter Coupled Logic (see also TTL)
ECLSS	Environmental Control and Life Support System [Space]
ECM	Electronic Counter Measure
ECM	European Common Market
ECMA	European Computer Manufacturers Association
ECO	Ecological
ECO	Electronic Central Office
ECO	Engineering Change Order
ECPA	Electronic Communications Privacy Act [US law]
ECS	Environmental Control System [Space]
ECT	ElectroConvulsive Therapy
ECV	Electric Cargo Vehicle [NASA OEXP]
ED&D	Expert Dungeons & Dragons
EDGAR	Electronic Data Gathering, Analysis, and Retrieval
EDI	Electronic Data Interchange
EDIF	Electronic Design Interchange Format
EDO	Extended Duration Orbiter [Space]
EDP	Electronic Data Processing
EDS	Electronic Data Systems
EDT	Eastern Daylight Time
EDTA	Ethylene Diamine Tetraacetic Acid
EDTCC	Electronic Data Transmission Communications Central
EE	Electrical Engineer
EE	Electrical or Electronics Engineer
EEC	European Economic Community
EEC	European Economic Comunity
EEG	ElectroEncephaloGram
EEL	Epsilon Extension Language
E&EO	Errors and Omissions Excepted
EEPROM	Electrically Erasable Programmable Read Only Memory
EFF	Electronic Frontier Foundation
e.g.	??? (Latin(?): for example)
EGA	Enhanced Graphics Adapter
EGP	Exterior Gateway Protocol [Internet]
EGRET	Energetic Gamma Ray Experiment Telescope (on GRO) [Space]
EHF	Extremely High Frequency (30-300GHz)
EIA	Electronic Industries Association
EINE	EINE Is Not Emacs
EISA	Extended Industry-Standard Architecture
EISS	European Intelligence Support System
EKG	ElectroKardioGramm (see ECG)
EL	ElectroLuminescent (as in display)
ELF	Extremely Low Frequency
ELO	Electric Light Orchestra
ELP	Emerson, Lake and Palmer (or Powell)
ELV	Expendable Launch Vehicle [Space]
E&M	``Ear and Mouth''; receive and transmit leads of a signalling system
EM	Enlisted Man (see EW)
EMA	Electronic Mail Association
EMACS	Editor MACroS
EMACS	Eight Megabytes And Constantly Swapping
E-MAIL	Electronic MAIL
EMF	ElectroMotive Force
EMF	ElectroMotive Force (voltage)
EMI	ElectroMagnetic Interference
EMP	Electromagnetic Pulse
EMPRESS EnvironMental Pulse Radiation Environment Simulator for Ships
EMR	ElectroMagetic Response
EMR	ElectroMagnetic Response
EMS	Electronic Message System
EMS	Extended Memory Specification
EMT	Emergency Medical Technician
EMU	ElectroMagnetic Unit
EMU	Extravehicular Mobility Unit [Space]
ENIAC	Electronic Numerical Integrator and Calculator
ENS	ENSign
EO	End Office [Telephony]
EO	Erasable Optical
EOF	End Of File
EOM	End Of Month
EOS	Earth Observing System [Space]
EOWG	Engineering and Operations Working Group (under FNC)
EP	Experience Points
EP	Extended Play
EPA	Environmental Protection Agency
EPOS	Engineering and Project-management Oriented Support system
EPRI	Electric Power Research Institute
EPROM	Erasable Programmable Read Only Memory
EPS	Encapsulated PostScript
EPT	Empire of the Petal Throne
EQ	Educational Quotient (see IQ)
ER	Emergency Room
ERA	Earned Run Average
ERA	Entity-Relationship-Attribute
ERA	Equal Rights Amendment
ERD	Entity-Relation Diagram
ERE	Entity Relationship Editor
ERT	Earth Resources Technology [Space]
ES	Expert System
ESA	European Space Agency
ESA	European Space Agency [Space]
ESAC	Electronic Systems Assistance Center
ESDI	Enhanced Standard Device Interface
ESE	East South East
ESF	Extended Superframe Format [Telephony]
ESM	Electronic Support Measures
ESnet	Energy Sciences network (DoE) [Networking]
ESO	European Southern Observatory
ESO	European Southern Observatory [Space]
ESP	Extra Sensory Perception
ESPS	Entropic Signal Processing System
ESS	Electronic Switching System [Telephony]
ESSEX	Experimental Solid State EXchange
EST	Eastern Standard Time
ET	Eastern Time
ET	Extra Terrestrial [Space]
ET	(Shuttle) External Tank [Space]
ETA	Estimated Time of Arrival
ET/ACC	External Tank/Aft Cargo Carrier (see also ET) [Space]
ETC	Et cetera, and so on...
ETD	Estimated Time of Departure
ETFD	Electronic Toll Fraud Device [Telephony]
ETH	Eidgn\:oessiche Technische Hochschule (Swiss Federal Institute of Technology)
ETLA	Extended Three Letter Acronym [Space]
ETO	Earth-to-Orbit [Space]
ETR	Eastern Test Range [Space]
ETS	Electronic Translator System
ETV	Education TeleVision
EUUG	European Unix User Group
EUV	Extreme UltraViolet
EUV	Extreme UltraViolet [Space]
EUVE	Extreme UltraViolet Explorer [Space]
EVA	ExtraVehicular Activity
EVA	ExtraVehicular Activity [Space]
EVX	Electronic Voice eXchange
EW	Electronic Warfare
EW	Enlisted Woman (see EM)
EWOS	European Workshop for Open Systems
FA	Football Association (British soccer--a word derived from Association)
FAA	Federal Aviation Agency [US Government]
FACD	Foreign Area Customer Dialing
FAO	Food and Agriculture Organization [US Government]
FAQ	Frequently Asked Questions [Space]
FAR	Federal Acquisition Regulations
FAS	Foreign Agricultural Service
FAS	Free Alongside Ship
FASST	Flexible Architecture Standard System Technology
FAST	Fast Auroral SnapshoT explorer [Space]
FAT	Foreign Area Translation
FAX	FAcsimile
FB	Freight Bill
FBI	Federal Bureau of Investigation [US Government]
FCC	Federal Communications Commission [US Government]
FCC	Federal Computer Conference
FCCSET	Federal Coordinating Committee for Science, Education and Technology (under OSTP) {Maybe Eng. for Edu.??}
FCO	Field Change Order
FCO	Frequency Controlled Oscillator
FCS	Frame Check Sequence
FDA	Food and Drug Administration [US Government]
FDDI	Fiber Digital Data Interface
FDDI	Fiber Distributed Data Interface
FDHD	Floppy Drive High Density
FDIC	Federal Deposit Insurance Corporation
FDIC	Federal Deposit Insurance Corporation [US Government]
FDM	Frequency Division Multiplexing
FDR	Franklin Delano Roosevelt [US President]
FE	Field Engineer (see also CE, SE)
FEA	Finite Element Analysis
FEDSIM	FEDeral Systems Integration and Management center
FEMA	Federal Emergency Management Agency
FEMF	Foreign EMF (q.v.) (a.k.a. Cross Battery) [Telephony]
FEPC	Fair Employment Practices Commission
FEPG	Federal Engineering Planning Group (of FNC under EOWG, originally of FRICC)
FERS	Federal Employees Retirement System
FET	Federal Excise Tax
FET	Field Effect Transistor
FFA	Future Farmers of America
FFT	Fast Fourier Transform
FFT	Fast Fourier Transform [Space]
FG-A	Feature Group A [Telephony] (Line Side termination for LD carriers)
FG-B	Feature Group B [Telephony] (Trunk Side termination for LD carriers (aka ENFIA B), 950 service)
FG-D	Feature Group D [Telephony] (Trunk Side termination for LD carriers, 1+ service)
FGS	Fine Guidance Sensors (on HST) [Space]
FHA	Federal Home Administration
FHA	Future Homemakers of America
FIB	Focused Ion Beam
FICA	Federal Insurance Contributions Act
FIDO	Fog Investigation Dispersal Operation
FIFO	First In First Out (as in registers and buffers)
FILO	First In Last Out (see also FIFO)
FIMS	Forms Interface Management System
FINE	FINE Is Not Emacs
FIO	Frequency In and Out
FIPS	Federal Information Processing Standard
FIR	Far InfraRed [Space]
FIR	Finite Impulse Response
FIRMR	Federal Information Resource Management Regulation
FIT	Federal Information Technologies, inc.
FITS	Flexible Image Transport System [Space]
FIX	Federal Inter-agency eXchange [Networking]
FL	Florida
FLACC	Full Level Algol Checkout Compiler
FLEA	Four Letter Extended Acronym
FLL	Fixed Loss Loop [Telephony]
FLOP	FLoating point OPeration
FLOPS	FLoating-point OPerations per Second
FLRA	Federal Labor Relations Authority
FM	Frequency Modulation
FMB	Federal Maritime Board
FMCS	Federal Mediation and Conciliation Service
FMR	Follow Me Roaming [Telephony]
FMS	Financial Management Service (Treasury Dept) [US Government]
FMS	Forms Management System
FNC	Federal Networking Council (formerly FRICC) [US Government] (under OSTP)
FO	Foreign Office
FO	Forward Observer
FOAC	Federal Office Automation Center
FOB	Free On Board
FOB	Full Of Bull (aperiodical of) [TMRC]
FOC	Faint Object Camera (on HST) [Space]
FOC	Free Of Charge
FOIA	Freedom Of Information Act
FOIMS	Field Office Information Management System
FOIRL	Fiber Optic Inter(?) Repeater(?) Link(?) [Ethernet]
FOOBAR	See FUBAR [Net jargon]
FOR	Free On Rail
FORCS	Faa's Operational Reporting Communication System
FORD	Fix Or Repair Daily [Humor]
FORD	Found On Road Dead [Humor]
FORTRAN FORmula TRANslator
FOS	Faint Object Spectrograph (on HST) [Space]
FOSE	Federal Office Systems Exposition
FOT	Fiber Optic Transceiver [Ethernet]
FOT	Free On Truck
FOV	Field Of View
FPA	Floating Point Accelerator
FPC	Fish Protein Concentrate
FPE	Floating Point Engine
FPHA	Federal Public Housing Authority
FPLA	Field Programmable Logic Array (see PLA)
FPM	Feet Per Minute
FPO	Field Post Office
FPO	Fleet Post Office
fps	Feet Per Second
FPU	Floating Point Unit
FQDN	Fully Qualified Domain Name [TCP/IP] (DNS)
FR	Frame Relay [Telephony, Networking]
FRACTAL FRACTional dimensionAL
FRED	Fred Resembles Emacs Deliberately
FRG	Federal Republic of Germany (West Germany)
FRICC	Federal Research Internet Coordinating Committee (now FNC, q.v.) [Networking, US Government]
FROG	Free Rocket Over Ground
FRPG	Fantasy Role Playing Game
FRS	Federal Reserve System
FS	Field Service
FS	File System
FS	Full Standard
FSF	Free Software Foundation
FSK	Frequency Shift Keying
FSLIC	Federal Savings and Loan Insurance Corporation
FSS	Federal Supply Service
FSW	Forward Swept Wings
Ft	Foot
FTAM	File Transfer And Management (ISO upscale FTP)
FTC	Federal Trade Commission
FTL	Faster Than Light
FTP	File Transfer Protocol (esp. of the TCP/IP suite)
FTS	Federal Telecommunications System [Telephony, US Government]
FTS	Flight Telerobotic Servicer [Space]
FUBAR	F***ed Up Beyond All Recognition/Repair
FUBAR	Fouled Up Beyond All Recognition/Repair
FUSE	Far Ultraviolet Spectroscopic Explorer [Space]
FW	Fringeworthy
FWD	Front Wheel Drive
FWHM	Full Width at Half Maximum [Space]
FX	Foriegn eXchange [Telephony]
FY	Fiscal Year
FYI	For Your Information
G	General audiences [Movie rating]
G	Gravity
GA	Gamblers Anonymous
GA	General Assembly
GA	General Average
GA	General of the Army
GA	Georgia
GAAP	Generally Accepted Accounting Principles
GAB	Group Audio Bridging [Telephony]
Gaia	Earth's self-sustaining Biosphere (Not an acronym, from some ancient language, I think)
GAN	Global Area Network
GAO	General Accounting Office [US Government]
GAR	Grand Army of the Republic
GARR	Gruppo Arminizzazione Rete por la Ricerca (Italian Research Network Harmonization Group)
GAS	Get-Away Special [Space]
GATT	General Agreement on Tariffs and Trade
GAW	Guaranteed Annual Wage
GAW	Guarenteed Annual Wage
GB	Gangbusters
GB	GigaByte
GB	Great Britain
GBIP	General Purpose Interface Bus
GBT	Green Bank Telescope [Space]
GC	Garbage Collection (LISP)
GC	Gas Chromatograph (or Chromatography)
GCA	Ground Controlled Approach
GCC	Gnu C Compiler
GCD	Ground Controlled Descent
GCL	Graphics Command Language
GCM	General Court Martial
GCR	Group-Coded Recording (magnetic tape, 6250 bpi)
GCT	Greenwich Civil Time
GCVS	General Catalog of Variable Stars [Space]
GDB	Gnu DeBugger
GDP	Gross Domestic Product
GDS	Great Dark Spot [Space]
GE	General Electric
GEM	Giotto Extended Mission [Space]
GEM	Graphics Environment Manager
GEO	Geosynchronous Earth Orbit [Space]
GHQ	General HeadQuarters
GHRS	Goddard High Resolution Spectrograph (on HST) [Space]
GHz	Giga HertZ (unit of frequency, 1,000,000,000 cycles per second)
GI	Galvanized Iron
GI	Gastro Intestinal (as in upper GI)
GI	General Issue
GI	Government Issue
GID	Group ID [UNIX]
GIF	Graphics Interchange Format
GIGO	Garbage In Garbage Out
GIN	Graphics INput
GISS	Goddard Institute for Space Studies
GKS	Graphical Kernel Standard
GKS	Graphics Kernel System
GM	Game Master
GM	General Manager
GM	General Motors [Corporate name, Automobile]
GM	Guided Missile
GMBH	Gesellschaft Mit Beschraenkter Haftung
GMC	Giant Molecular Cloud [Space]
GMD	Gesellschaft f\:ur Mathematik und Datenverarbeitung (German Institute for Mathematics and Data Processing)
GMRT	Giant Meter-wave Radio Telescope [Space]
GMT	Greenwich Mean Time (also called UT)
GNP	Gross National Product
GNU	GNU's Not Unix
GOES	Geostationary Orbiting Environmental Satellite [Space]
GOES	Geostationary Orbiting Environmental Satellites [Space]
GOSIP	Government Open Systems Interconnection Profile (calls for government procurement of ISO/CCITT products)
GOSIP	Government OSI Profile
GP	General Practitioner
GP	General Purpose (RR engines and origin of Jeep) [Railroading, Automobile]
GPC	General Purpose Computer [Space]
GPI	Graphics Programming Interface
GPIB	General Purpose Interface Bus
GPIB	General-Purpose Interface Bus
GPL	GNU General Public Licence
GPO	General Post Office
GPO	Government Printing Office
GPS	Global Positioning System
GPS	Global Positioning System [Space]
GQ	General Quarters
GRB	Gamma Ray Burst(er)
GREP	Global Regular Expression Print, g/re/p, (UNIX command)
GREP	Global Regular Expression Print [UNIX]
GRO	Gamma Ray Observatory [Space]
GRS	Gamma Ray Spectrometer (on Mars Observer) [Space]
GRS	Great Red Spot [Space]
GS	General Schedule
GS	Glide Slope
GSA	General Services Administration
GSA	General Services Adminstration [US Government]
GSA	Girl Scouts of America
GSBCA	General Services administration Board of Contract Appeals
GSC	Guide Star Catalog (for HST) [Space]
GSFC	Goddard Space Flight Center (Greenbelt, MD) [NASA, Space]
GSI	Gesellschaft f\:ur Schwerionenforschung (German Federal Research Institute for Heavy Ion Research)
GSM	Global System Mobile
GSM	Groupe Speciale Mobile (Committee Designing preceding)
GSTS	Ground-based Surveillance and Tracking System
GT	Gross Ton
GTE	General Telephone and Electric [Corporate name]
GTO	Geostationary Transfer Orbit [Space]
GTSI	Government Technology Services, inc.
GUI	Graphical User Interface
GW	Gamma World
GWEN	Ground Wave Emergency Network
GWM	Generic Window Manager [X]
H	Harn
H	Height
HACD	Home Area Customer Dialing
HAL	Heuristically programmed ALgorithmic computer (movie 2001)
HAM	Hold And Modify
HAO	High Altitude Observatory [Space]
Hb	HemogloBin
HBM	Her British Majesty; His British Majesty
HBO	Home Box Office
HC	Holy Communion
HC	House of Commons
HCFA	Health Care Financing Administration
HCFC	hydrochlorofluorocarbon [Chemical]
HCL	High Cost of Living
HD	Hard Disk
HD	Heavy Duty
HD	Henry Draper catalog entry [Space]
HDA	Head Disk Assembly (in winchester disk drives)
HDBV	Host Data Base View
HDL	High Density Lipoprotein
HDLC	High-level Data Link Control [Networking]
HDTV	High Definition Television
HE	His Eminence
HE	His Excellency
HEAO	High Energy Astronomical Observatory [Space]
HEDM	High Energy-Density Matter [Space]
HEMP	Help End Marijuana Prohibition
HEO	High Earth Orbit [Space]
HEPnet	High Energy Physics network [Networking]
HERO	Hazards of Electromagnetic Radiation to Ordnance
HF	High Fantasy
HF	High Frequency (3-30MHz)
HFE	Human Factors Engineering
HFS	Hierarchical File System
HGA	High Gain Antenna [Space]
HHS	(US Department of) Health and Human Services
HI	Hawaii
HIIPS	Hud Integrated Information Processing Services
HLC	Heavy Lift Capability [Space]
HLL	High-Level Language
HLV	Heavy Lift Vehicle [Space]
HMC	Halley Multicolor Camera (on Giotto) [Space]
HMOS	High performance Metal Oxide Semiconductor (see MOS)
HMS	His/Her Majesty's Ship
HMT	His/Her Majesty's Transport
HNPA	Home Numbering Plan Area [Telephony]
HOBIS	HOtel Billing Information System 
HOL	High-Order System
HOTOL	HOrizontal Take-Off and Landing
HP	Hewlett Packard, Inc. [Corporate name]
HP	High Pressure
HP	Higher Power (sort of an AA "in" term, usually God)
HP	Hit Points
HP	HorsePower
HPGe	High Purity Germanium
HPL/T	High-Productivity Languages/Tools
HQ	HeadQuarters
HR	Hertzsprung-Russell (diagram) [Space]
HR	House of Representatives
HRH	Her Royal Highness
HRH	His Royal Highness
HRI	High Resolution Imager (on ROSAT) [Space]
HS	High School
HSB	Hue, Saturation, Brightness
HSP	High Speed Photometer (on HST) [Space]
HST	Hawaiian Standard Time
HST	Hubble Space Telescope [Space]
HT	High Tension (as in electric power transmission)
HTK	Hits To Kill
HUAC	House Unamerican Activities Committee
HUD	Heads Up Display
HUD	Housing and Urban Development [US Government]
HUPD	Harvard University Police Department
HUT	Hopkins Ultraviolet Telescope (ASTRO package) [Space]
HV	High Voltage
HVAC	Heating, Ventilation, and Air Conditioning
HW2000	Highway 2000
HWM	High-Water Mark
Hz	HertZ (unit of frequency, cycles per second)
IAB	Internet Activities Board [Networking]
IAEA	International Atomic Energy Agency
IANA	Internet Assigned Numbers Authority (IANA@ISI.EDU)
IATA	International Air Transport Association
IAU	International Astronomical Union [Space]
IAUC	IAU Circular [Space]
IBM	Ingrained Batch Mentality
IBM	International Business Machines, Inc. [Corporate name]
IBM	Itty Bitty Machines
IBT	Illinois Bell Telephone
IC	Integrated Circuit
IC	Interexchange Carrier [Telephony] (see also IEC, IXC)
ICB	Interstate Computer Bank
ICBM	InterContinental Ballistic Missile
ICE	In-Circuit Emulator
ICE	International Cometary Explorer [Space]
ICI	Imperial Chemical Industries
ICJ	International Court of Justice
ICL	International Computers Ltd.
ICMP	Internet Control Message Protocol
ICP	Integrated Channel Processor
ICP	Inventory Control Points
ICRC	International Cosmic Ray Conference
ID	Idaho
ID	IDentification
IDA	Intercommunication Data Areas
IDA	International Dark-sky Association [Space]
IDA	International Development Association
IDDD	International Direct Distance Dial [Telephony]
IDE	Interactive Development Environments, inc
IDF	Intermediate Distributing Frame [Telephony]
IDL	Interactive Data Language [Space]
IDV	Interlibrational Derived Vehicle [Space]
i.e.	???? (Latin(?): in other words (?))
IE	Indo-European
IEC	Inter-Exchange Carrier [Telephony] (see also IC, IXC)
IEE	Institute of Electrical Engineers [UK]
IEEE	Institute of Electrical and Electronic Engineers
IETF	Internet Engineering Task Force
IF	Intermediate Frequency (as in IF stage)
IFB	Invitation For Bids
IFC	International Finance Corporation
IFC	International Freighting Corporation
IFF	Identification - Friend or Foe
IFF	Interchange File Format
IFLA	International Federation of Library Associations
IFR	Instrument Flight Rules [Aviation]
IGES	Initial Graphics Exchange Standard
IGM	InterGalactic Medium [Space]
IGY	International Geophysical Year
IGY	International Geophysical Year [Space]
IHP	Indicated HorsePower
IHS	Integrated Hospital Support
IIA	Information Industry Association
IIE	Institute of Industrial Engineers
IIHF	International Ice Hockey Federation
IIL	Integrated Injection Logic
ILO	International Labor Organization
ILS	Instrument Landing System
ILV	Industrial Launch Vehicle [Space]
IMF	International Monetary Fund
IMHO	In My Humble Opinion [Net jargon]
IMO	In My Opinion [Net jargon]
IMP	Interface Message Processor [ARPANET/MILNET] (replaced by PSN)
IMSL	International Mathematical Subroutine Library
IN	Indiana
INADS	INitialization and ADministration System [Telephony]
INRA	Iesus Nazerenus Rex Iudaeorum (Jesus of Nazareth, King of the Jews)
INRIA	Institut National de Recherche en Informatique et Automatique
INS	Immigration and Naturalization Service
In-situ In Place [Latin]
INSTITUTE	INSTITUTE's Name Shows That It's Totally Unrelated To EMACS
INTAP	INteroperability Technology Association for information Processing
INWATS	INward Wide Area Telephone Service [Telephony]
I/O	Input/Output
IO	Input/Output (sometimes I/O)
IOC	International Operating Center [Telephony, US]
IOD	Identified Outward Dialing
IOOF	International Order of Odd Fellows
IOTA	Infrared-Optical Telescope Array [Space]
IOTA	International Occultation Timing Association [Space]
IOU	I Owe you(U)
IP	Information Provider [Telephony]
IP	Innings Pitched
IP	Intermediate Point
IP	Internet Protocol
IPC	Inter-Process Communication
IPE	Integrated Programming Environment
IPMS	InterPersonal Message Services
IPS	Inertial Pointing System [Space]
IPS	Information Processing Standards
IPSE	Integrated Project-Support Environment
IQ	Intelligence Quotient (see EQ)
IR	Index Register
IR	Infra-Red
IRA	Individual Retirement Account
IRA	Irish Republican Army
IRAF	Image Reduction and Analysis Facility [Space]
IRAS	InfraRed Astronomical Satellite [Space]
IRBM	Intermediate Range Ballistic Missile
IRDS	Information Resource Dictionary Standard
IRDS	InfraRed Detection Set
IRE	Institute of Radio Engineers (old name for the now IEEE, which see)
IRM	Information Resources Management
IRMS	Information Resources Management Service
IRS	Internal Revenue Service
IRTF	Internet Research Task Force
IS	Information Systems
IS	International Standard [ISO] (Beyond the DIS Stage)
ISA	Industry-Standard Architecture
ISAM	Indexed Sequential Access Method
ISAS	Institute of Space and Astronautical Science (Japan) [Space]
ISBD	International Bibliographic Description
ISC	Information Services Center
ISC	International Switching Center
ISCH	Interstitial-Cell-Stimulating Hormone (same as LH)
ISDN	Integrated Services Digital Network [Telephony]
ISDT	Integrated Systems Development Tool
ISEE	International Sun Earth Explorer (usually ISEE-3)
ISF	Information Systems Factory
ISFUG	Integrated Software Federal User Group
ISI	Information Sciences Institute
ISM	InterStellar Medium [Space]
ISO	Infrared Space Observatory [Space]
ISO	International Organization for Standardization 
ISO	International Standards Organization [Space]
ISODE	ISO Development Environment
ISOO	Information Security Oversight Office
ISPM	International Solar Polar Mission
ISPM	International Solar Polar Mission (now Ulysses) [Space]
ISR	Institute of Snow Research
ISRG	Independent Space Research Group
ISV	Independent Software Vendor
ISY	International Space Year [Space]
IT	Industrial Technology
IT	Information Technology
ITC	Inter-Task Communication
ITS	Incompatible Timesharing System
ITT	International Telephone and Telegraph
ITU	International Telecommunications Union
ITUSA	IT Users Standards Association
IUE	International Ultraviolet Explorer [Space]
IUS	Inertial Upper Stage
IUS	Inertial Upper Stage [Space]
IUV	Interlibrational Utility Vehicle [Space]
IXC	Inter-eXchange Carrier [Telephony] (see also IC, IEC)
IXI	International (pan-European) X.25 Infrastructure
JACM	Journal of the Association for Computing Machinery
JANET	Joint Academic Network (UK)
JBS	John Birch Society
JC	Jesus Christ
JC	Joint Compound (plumbing)
JC	Julius Caesar
JC	Junior College
JCA	Jewelry Crafts Association
JCAC	Joint Civil Affairs Committee
JCAE	Joint Committee on Atomic Energy
JCEE	Joint Council on Economic Education
JCET	Joint Council on Educational Television
JCS	Joint Chiefs of Staff
JD	Justice Department
JDS	John Dewey Society
JEM	Japanese Experiment Module (for SSF) [Space]
JES	John Ericsson Society
JET	Joint European Torus (fusion research)
JFK	John F. Kennedy
JFK	John F. Kennedy (international airport)
JFMIP	Joint Financial Management Improvement Program
JGR	Journal of Geophysical Research
JGR	Journal of Geophysical Research [Space]
JI	Justice, Inc.
JIC	Joint Intelligence Center
JIC	Just in Case
JILA	Joint Institute for Laboratory Astrophysics [Space]
JIM	Job Information Memorandum
JINTACCS	Joint INteroperability of TActical Command and Control Systems
JIS	Japan Industrial Standards
JISC	Japanese Industrial Standards Committee
JIT	Just In Time
JMS	John Milton Society
JNT	Joint Network Team (UK)
JO	Job Order
JO	Junior Officer
JOVE	Jonathan's Own Version of Emacs
JOVIAL	Jules Own Version of the International Algorithmic Language
JPL	Jet Propulsion Laboratory
JPL	Jet Propulsion Laboratory [Space]
JRC	Junior Red Cross
JSC	Johnson Space Center
JSC	Johnson Space Center (NASA) [Space]
JSD	Jackson System Development
JSRC	Joint Services Review Committee
JTIDS	Joint Tactical Information Distribution Systems
JV	Junior Varsity
JvNC	John von Neumann (Super Computer) Center
JvNCnet John von Neumann (Super Computer) Center network
K	Kilo- (metric 1000)
K9	canine (K9 corps - army dogs)
KAIST	Korean Advanced Institute of Science and Technology
KAO	Kuiper Airborne Observatory [Space]
KB	KiloByte
KC	King's Counsel (QC when queen reigning)
KC	Knights of Columbus
KD	Kiln Dried
KD	Knocked Down
KDCI	Key Display Call Indicator
KERMIT	Kl-10 Error-free Reciprocal Micro Interconnect over Tty lines
KET	Kentucky Educational Television
KHz	Kilo HertZ (unit of frequency, 1000 cycles per second)
KI	Kiwanis International
KIA	Killed In Action
KIAS	Knot Indicated Air Speed
Km	Kilometers
KO	Knock Out [Boxing, Electric]
KP	Key Pulse [Telephony]
KP	Kitchen Police
KPNO	Kitt Peak National Observatory
KPO	KeyPunch Operator
KQC	King's College London
K&R	Kernighan and Ritchie, the c programming language
KS	King's Scholar
KSC	Kennedy Space Center (NASA) [Space]
KSU	Key System Unit [Telephony]
KTB	Cretaceous-Tertiary Boundary (from German) [Space]
KTS	Key Telephone System [Telephony]
KTU	Key Telephone Unit [Telephony]
KWIC	Key Word In Context
KY	Kentucky
L1	Lagrange Point #1 35,000 Miles above moon [Space]
L2	Lagrange Point #2 40,000 Miles behind moon [Space]
L3	Lagrange Point #3 (?? 35,000 Miles below moon) [Space]
L4	Lagrange Point #4 240,000 mile Earth orbit [Space]
L5	Lagrange Point #5 240,000 mile Earth orbit [Space]
LA	Los Angeles
LA	Louisiana
LA	Low Altitude
LADAR	LAser Detection And Ranging
LAM	Master of Liberal Arts
LAMA	Local Automatic Message Accounting [Telephony]
LAN	Local Apparent Noon
LAN	Local Area Network
LANL	Los Alamos National Laboratory [Space]
LANL	Los Alamos (NM) National Laboratory
LAPB	Link Access Procedure (Balanced)
LAPD	Link Access Procedure (??)
LAPD	Los Angeles (CA, US) Police Department
LAR	Local Acquisition Radar
LaRC	Langley Research Center (NASA) [Space]
LASER	Light Amplification by Stimulated Emission of Radiation
LAT	Local Apparent Time
LATA	Local Access and Transport Area [Telephony]
LAX	Los Angeles International Airport
LB	Light Bomber
LB	pound (LiBra)
LBHS	Long Beach High School
LBL	Lawrence Berkeley (Calif.) Labs
LBS	Pounds
LC	inductor-Capacitor circuit (as in filters, L is symbol inductance)
LCD	Liquid Crystal Display
LCD	Lowest Common Denominator
LCDR	Lieutenant Commander
LCL	Less than Carload Lot [Railroading]
LCL	Lunar Cargo Lander [NASA OEXP]
LCM	Least Common Multiple
LCM	Life Cycle Management
LCS	Laboratory for Computer Science (of MIT)
LCT	Landing Craft Tanks
LD	Long Distance [Telephony]
LDC	Long Distance Carrier [Telephony]
LDEF	Long Duration Exposure Facility [Space, NASA]
LDF	Large Deployable Reflector [Space]
LDL	Low Density Lipoprotein
LDX	Long Distance eXtender [Telephony]
LEAP	Low-power Enhanced At Portable
LEC	Local Exchange Carrier [Telephony]
LED	Light Emitting Diode
LEM	Lunar Excursion Module (a.k.a. LM) (Apollo spacecraft) [Space]
LEO	Low Earth Orbit [Space]
LEP	Large Electron-Positron collider [CERN]
LeRC	Lewis Research Center (NASA) [Space]
LEST	Large Earth-based Solar Telescope [Space]
LF	Low Frequency (30-300KHz)
LFSA	List of Frequently Seen Acronyms (!) [Space]
LGA	Low Gain Antenna [Space]
LGM	Little Green Men [Space]
LH	Left Hand
LH	Liquid Hydrogen (also LH2 or LHX) [Space]
LH	Lower Half
LH	Luteinizing Hormone (same as ISCH)
LHC	Large Hadron Collider [CERN]
LHD	Litterarum Humaniorum Doctor (doctor of human letters)
LHS	Left Hand Side
LI	Long Island
LIFIA	Laboratoire d'Informatique Fondamentale et d'Intelligence Artificielle
LIFO	Last In First Out (see FIFO)
LINC	Laboratory INstrument Computer
LISA	Large Installation Systems Administration (USENIX specific?)
LISP	LISt Processing Language
LIU	Line Interface Unit
LL	Late Latin
LL	Long Lines [Telephony]
LLB	Legum Baccalaureus (bachelor of laws)
LLD	Legum doctor (doctor of laws)
LLN	Line Link Network [Telephony]
LLNL	Lawrence Livermore National Laboratories
LLO	Low Lunar Orbit [Space]
LLOX	Lunar Liquid Oxygen [Space]
LLP	Line Link Pulsing [Telephony]
LM	Life Master (Contract Bridge ranking)
LM	Lunar Module (a.k.a. LEM) (Apollo spacecraft) [Space]
LMC	Large Magellanic Cloud (see SMC)
LMC	Large Magellanic Cloud [Space]
LMOS	Line Maintenance Operations System [Telephony, AT&T]
LN2	Liquid N2 (Nitrogen) [Space]
LNG	Liquified Natural Gas
LOA	Lands of Adventure
LOFT	Launch Operations Flight Test [Space]
LOOPS	Lisp Object Oriented Programming System
LOP	Lines Of Position
LOSF	Lunar Orbit Staging Facility [Space]
LOTS	Low Overhead Timesharing System
LOX	Liquid Oxygen
LOX	Liquid OXygen [Space]
LP	Long Play(ing) (record)
LP	Low Pressure
LPC	Linear Predictive Coding (speech processing)
LPDA	Link Problem Determination Aid
LPF	League for Programming Freedom
LPG	Liquefied Petroleum Gas
LPG	Low Pressure Gas
LPL	Lunar Personnel Lander [NASA OEXP]
LPN	Licensed Practical Nurse
LPP	Licensed Program Products
LPR	Line PrinteR
LPT	Lunar Propellant Tanker [NASA OEXP]
LPV	Lunar Piloted Vehicle [NASA OEXP]
LRB	Liquid Rocket Booster [Space]
LRBM	Long Range Ballistic Missile
LRC	Longitudinal Redundancy Character
LRU	Least Recently Used
LRU	Line Replaceable Unit
LRV	Light Rail Vehicle [Railroading]
LS	Left Side
LS	Letter Signed
LS	Locus Sigilli (place of seal)
LSAP	Logical(?, maybe Link) Service Access Point [OSI, Networking]
LSB	Least Significant Bit; Least Significant Byte
LSB	Lower Side Band
LSC	Lecture Series Committee (of MIT)
LSC	LightSpeed C
LSD	Least Significant Digit
LSD	LySergic acid Diethylamide
LSD	pounds (Libra), shillings (Sestertii), and (old) pence (Denarii)
LSI	Large Scale Integration
LSP	LightSpeed Pascal
LSR	Local Standard of Rest [Space]
LSS	Life Support System
LSS	Loop Switching System
LSSD	Level-Sensitive Scan Detection
LT	Long Ton
LT	Low Tension
LTC	Lieutenant Colonel
LTJG	Lieutenant Junior Grade
LTL	Less than Truckload Lot
LTP	Lunar Transient Phenomenon [Space]
LUG	Local Users Group
LUT	Look-Up Table
LWM	Low-Water Mark
LWT	London Weekend Television [Corporate name]
LZ	Landing Zone
M	Mega- (metric 10^6)
m	meter(s)
m	milli- (metric 1/1000)
M	Miniatures
MA	Massachusetts [US state postal designation]
MAAP	Maintenance And Administration Panel
MAC	an MIT interdepartmental lab (stands for many things) (renamed to LCS)
MAC	Media Access Control
MAC	Medium Access Control
MAC	Military Air Command
MACSYMA project MAC's SYmbolic MAnipulation System
MAD	Mutual Assured Destruction
MADD	Mothers Against Drunk Driving
MAG	Magazine
MAN	Metropolitan Area Network
MAP	Manufacturing Automation Protocol
MAP/TOP Manufacturing Automation Protocol/Technical Office Protocol
MARBI	MAchine Readable form of Bibliographic Information
MARC	MAchine Readable card Catalog
MARS	Multiuser Archival and Retrieval System
MASC	Multiple Award Schedule Contract
MASER	Microwave Amplification by Stimulated Emission of Radiation
MASH	Mobile Army Surgical Hospital
MAST	Multi-Application SOnar Trainer
MAT-CALS	Marine Air Traffic-Control And Landing System
MAU	Math Acceleration Unit
MAU	Media Access Unit
MAU	Medium Access Unit
MB	Manned Base [Space]
MB	MegaByte
MBA	Master Business Administration
MBTA	Massachusetts Bay Transportation Authority
MC	Master of Ceremonies
MCA	Micro Channel Architecture
MCAE	Mechanical Computer Aided Engineering
MCC	Master Control Console
MCC	Microelectronics and Computer technology Corporation
MCC	Mission Control Center [Space]
MCP	Master Control Program
MCP/AS	Master Control Program/Advanced System
MCPO	Master Chief Petty Officer
MCSV	Mars Crew Sortie Vehicle [NASA OEXP]
MD	Doctor of Medicine
MD	Maryland
MD	Maryland [US state postal designation]
MD	Medical Doctor
MD	Months after Date
MDAS	Magnetic Drum Auxiliary Sender
MDC	Metropolitan District Commision (Mass State Agency)
MDE	Modular Design Environment
MDF	Main Distribution Frame [Telephony]
MDRE	Mass Driver Reaction Engine [Space]
MDT	Mean Down Time
ME	Maine
ME	Mechanical Engineer
MECO	Main Engine CutOff [Space, Shuttle]
MEd	Master of EDucation
MERP	Middle-Earth Role Playing
MeV	Million Electron Volts
MF	Medium Frequency (300-3000KHz)
MF	Middle French
MF	Multi-Frequency [Telephony]
MFA	Master Fine Arts
MFA	Museum of Fine Arts [Boston]
MFJ	Modified Final Judgment [Telephony]
MFLOPS	Million FLoating-point OPerations per Second (see also FLOPS)
MFM	Modified Frequency Modulation
MFS	Macintosh File System
MG	Machine Gun
MG	Major General
MG	Militar