c centi-(centímetro) (medida métrica 1/100 métros)
C programming language 
CA California
CA Chartered Accountant
CA Chief Accountant
CA Chronological Age
CA Collision Avoidance (como em CSMA/CA (q.v.))
CAB Civil Aeronautics Board
CACM Communications of the Association for Computing Machinery
CAD Computer Aided Design (às vezes visto como 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 (às vezes visto como CAD/CAM)
CAM Content Addressable Memory
CAMA Centralized Automatic Message Accounting (Telefonia)
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 (nome de companhia)
CBW Chemical and Biological Warfare
CC C (linguagem) Compiler
CC Carbon Copy
CCA Computer Corporation of America (nome de companhia)
CCAFS Cape Canaveral Air Force Station (Espacial)
CCC Canadian Committee on Cataloging
CCC Civil(ian) Conservation Corps
CCC Command, Control, and Communications (às vezes C^3)
CCC Concourse Computer Center [MIT]
CCCCM CCC CounterMeasures (às vezes C^3CM)
CCCI Command, Control, Communications, and Intelligence
CCD Charge Coupled Device (veja também CID)
CCD Charge-Coupled Device (Espacial)
CCDS Centers for the Commercial Development of Space (Espacial)
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 (Telefonia)
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 (Música)
CCRI Community College of Rhode Island (nome de companhia)
CCRP Continuously Computed Release Point
CCS Hundred Call Seconds (Telefonia)
CCS7 Common Channel Signalling (version #7) [Telefonia, AT&T]
CCSA Common Control Switching Arrangement (Telefonia)
CCTA Central Computer and Telecommunications Agency
CCTV Closed Circuit TeleVision
CD Carrier Detect (corretamente DCD (q.v.)) (EIA RS-232-C)
CD Certificate of Deposit
CD Civil Defense
CD Collision Detection (como em 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. (nome de companhia)
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 (Espacial)
CDSF Commercially Developed Space Facility
CDT Central Daylight Time
CDU Control Display Unit
CE Chemical Engineer
CE Civil Engineer
CE Common Era (substituível por AD)
CE Corps of Engineers
CE Customer Engineer (veja também FE, SE)
CEA Commissariat a l'Energie Atomique (Comissão francesa de energia atômica)
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 (Espacial)
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 (antigamente Conseil) Europeenne pour la Recherche Nucleaires
CERT Computer Emergency Response Team
CEVI Common Equipment Voltage Indicator
CF Carry Forward
CF Coin First (payphone) (Telefonia)
CF Cystic Fibrosis (infecção)
CFA Center For Astrophysics (Espacial)
CFC Chloro-FluoroCarbon (Química)
CFC Combined Federal Campaign
CFD Computational Fluid Dynamics
CFHT Canada-France-Hawaii Telescope (Espacial)
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 (Espacial)
CHI Chill: Adventures into the Unknown
CHOTS Corporate Headquarters Office Technology System
CHP California Highway Patrol
CI Cubic Inches
CIA Central Intelligence Agency (Governo americano)
CIA Culinary Institute of America (Hyde Park, NY)
CIC Carrier Identification Codes (Telefonia) (10XXX códigos)
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 (Telefonia) (veja também: CLID, ANI)
CID Central Institute for the Deaf
CID Charge Injection Device (veja também 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 (Espacial)
CISC Complex Instruction Set Computer
Cislunar The space between the Earth and the Moon
CIT California Institute of Technology
CIT Case Institute of Technology (parte de CWRU, Cleveland, OH)
CIT Circumstellar Imaging Telescope (Espacial)
CLASP Comprehensive Logistics Automated Support Program
CLASS Custom Local Area Signaling Service (Telefonia)
CLI Command Line Interpreter
CLID Calling Line ID (Telefonia) (veja também: 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 (nave espacial Apollo) (Espacial)
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 (veja também 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 [Nome de companhia, Railroading]
CN/A Customer Name / Address (Telefonia)
CNI Common Network Interface [Telefonia, AT&T] (Departamento da AT&T)
CNN Cable News Network
CNO Carbon-Nitrogen-Oxygen (Espacial)
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 (Espacial)
CO Cash Order
CO Central Office (Telefonia)
CO Colorado
CO Commanding Officer
CO Conscientious Objector
C/O in Care Of
COB Close Of Business
COBE COsmic Background Explorer (Espacial)
COBOL COmmon Business Oriented Language
COC Call of Cthulhu
COCOT Customer Owned, Coin Operated Telephone (Telefonia)
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 (em GRO) (Espacial)
COMSAT Communications Satellite (Espacial)
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 (Espacial)
COT Card Or Tape (NCR)
CP Campus Police (MIT, outros provavelmente também)
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 (às vezes CP/M)
CPM Control Program Monitor (às vezes 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 13 decimal)
CRA Cambridge Redevelopment Authority
CRAF Comet Rendezvous / Asteroid Flyby (Espacial)
CRAM Card Random Access Memory (NCR, mas também outros)
CRC Chemical Rubber Company
CRC Cyclic Redundancy Check
CREG Concentrated Range Extension with Gain
CREN The Corporation for Research and Educational Networking (cobinado com BITNET e CSNet)
CRRES Combined Release / Radiation Effects Satellite (Espacial)
CRRES Combined Release and Radiation Effects Satellite [NASA]
CRT Cathode Ray Tube (também referência genérica para um 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 (nave espacial Apollo) (Espacial)
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 (combinado com BITNET para criar 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 (Telefonia)
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 (Espacial)
CT Connecticut
CTC Canadian Transport Commission
CTC Centralized Traffic Control (Rede ferroviária)
CTD Computing and Telecommunications Division
CTIO Cerro Tololo Inter-american Observatory
CTIO Cerro Tololo Interamerican Observatory (Espacial)
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 (Jargão usado na Net)
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
® Pesquisa RXA