| Acronym | Definition |
|---|
| C | Copyright (usually written ©) |
| C | 100 (Roman numeral) |
| C | Average grade |
| C | Cell (phone; science) |
| C | Transport (US military aircraft designation for transport aircraft since 1962) |
| C | Battery Size |
| C | Celsius/Centigrade |
| c | symbol for the speed of light (in a vacuum, 299,792,458 meters per second) |
| C | Click |
| C | Cum (Latin: With, often seen with a bar over the c) |
| C | See |
| C | Company |
| C | Control |
| C | Center (basketball) |
| C | Center (football) |
| C | Complete |
| C | Current (action code) |
| C | College |
| C | Case |
| C | Cost |
| C | Category (abstract algebra) |
| C | Color |
| C | Close |
| C | Clear |
| C | Club (class airfare) |
| C | Chicago |
| C | Common |
| C | Individual (IRB) |
| C | Sea |
| C | Correct |
| C | Canadian |
| C | Century |
| C | C Programming Language |
| C | Combined (DoD) |
| C | Corporate |
| C | Centre (Canada Post road designation) |
| C | Clubs (playing cards) |
| C | Cookie |
| C | Cable |
| C | Corporation |
| C | Character |
| C | Caught |
| C | Cup |
| C | Chief |
| C | Committee |
| C | Chapter |
| C | Compliance (Network World) |
| C | Chemical |
| C | Charlotte, NC (mint mark on coinage 1837-1861) |
| C | Charlie |
| C | Economy Class (Air Freight) |
| C | Air Post (philatelic catalog prefix for non-ground stamps) |
| C | Corner (welded joint type) |
| C | Connect (ITU-T) |
| C | Cycle |
| C | Castle |
| C | Constant |
| C | Prince Edward Island (Canada Post designation) |
| C | Confidential |
| C | Circuit |
| C | Catholic |
| C | Chairman |
| C | Cent |
| C | Congress |
| C | Collector (transistor; electronics) |
| C | Carbon |
| C | Candle |
| C | Calm |
| C | Combinations (probability) |
| C | Consumption (economics) |
| C | Cliff (Stores 100 code) |
| C | Circa |
| C | Conservative |
| C | Commonwealth |
| C | Container (SDH) |
| C | Cloudy |
| C | Colon (currency of Costa Rica and El Salvador) |
| C | Cork (Irish car registration) |
| C | Cairo (Egyptian automobile license plate) |
| C | Cubic |
| C | Codex |
| C | Calorie |
| C | Compute(r) |
| C | Cough |
| C | Carat |
| C | Catcher (baseball) |
| C | Conduit |
| C | Cocaine |
| C | Canceled |
| C | Cyan |
| C | Affirmative (logging abbreviation) |
| C | Clerical (for ACG duties) |
| C | Clock Mode (aviation) |
| C | Circumference |
| C | Countess |
| C | Coefficient |
| C | Cessna (civilian aircraft) |
| C | Correlations |
| C | Chromosome (as in banding) |
| C | Curie |
| C | Clockwise |
| C | Constant of Integration (calculus) |
| C | Carbone (French: Carbon) |
| C | Comptroller |
| C | Consonant (speech) |
| C | Citigroup (stock symbol) |
| C | CitiGroup, Inc. (NYSE symbol) |
| C | Ascorbic Acid (vitamin) |
| C | Coverage factor |
| C | Conseco |
| C | Circling (approach and landing charts) |
| C | C Major (music) |
| C | Capacitance |
| C | Exposure Concentration (environment) |
| C | Centimeter |
| C | Cranial Nerve |
| C | Cysteine (amino acid) |
| C | Cedi (currency of Ghana) |
| C | Court of Chancery (UK) |
| C | Set of Complex Numbers (mathematics) |
| C | Coulomb |
| C | Centavo |
| C | Centime |
| C | Convective |
| C | Ceiling Limit (weather reports) |
| C | Contralto |
| C | Centum (relating to an Indo-European language pronunciation) |
| C | Cool Breeze (rapper) |
| C | Centi (abbreviation of abbreviation for 1/100) |
| C | Central Standard Time (as used in time groups) |
| C | Cytosine |
| c | Centerpartiet (Swedish political party) |
| C | Caesarian |
| C | Nicaraguan Cordoba (national currency) |
| C | Cervical Vertebra (prefix, as in C-1, C-2) |
| C | Cycloplegic |
| C | Congius (Latin: Colt) |
| C | C Programming Language Source Code (file name extension) |
| C | Fresnel Cosine Integral |
| C | Federal Reserve Bank of Philadelphia, Pennsylvania (designates original point of circulation of a dollar bill) |
| C | creeping line pattern (US DoD) |
| C | Musical pitch/note |
| C | Undenominated US Stamp (20 cents, introduced 1 Nov 1981) |