| Acronym | Definition |
|---|
| CO | Company |
| CO | Central Office (telecommunications/telephony) |
| CO | Colorado (US postal abbreviation) |
| CO | Commanding Officer |
| CO | Carbon Monoxide |
| CO | Call-Out |
| CO | Colombia |
| CO | Change Order |
| CO | Course |
| CO | Cash Out (mortgage refinancing) |
| CO | County |
| CO | Conference |
| CO | Current Operations |
| CO | Chief Officer |
| CO | Checkout |
| CO | Command |
| CO | Cabinet Office |
| CO | Como (Lombardia, Italy) |
| CO | Colton (blood group) |
| CO | Certificate of Origin |
| CO | Controlling |
| CO | Community Organizer (Philippines) |
| CO | Compliance |
| CO | Chill Out |
| CO | Connection Oriented |
| CO | Combat (game, Natural Selection) |
| CO | Community Outreach |
| CO | Cellular One |
| CO | Complain Of |
| CO | crude oil |
| CO | Charlotte Observer (newspaper) |
| CO | Compliance Officer |
| CO | Cardiac Output |
| CO | Cobalt |
| CO | Colchester (postcode, United Kingdom) |
| CO | Certificate of Occupancy |
| CO | Conan O'Brien |
| CO | Correctional Officer |
| CO | Communications Officer |
| CO | Castor Oil |
| CO | Colonial Office (UK) |
| CO | Cargo Operations |
| CO | Commissioned Officer |
| CO | Compliance Order |
| CO | Captain Obvious |
| CO | Cutoff |
| CO | Chinese Orchestra |
| CO | Cornish (linguistics) |
| CO | Compañía (Spanish) |
| CO | Continental Airlines (airline code) |
| CO | Correction Officer |
| CO | Clinical Operations |
| CO | Covert Operations (gaming) |
| CO | Clean Out (sewers/drains) |
| CO | Combinatorial Optimization (workshop) |
| CO | Contracting Officer |
| CO | Cash Order |
| CO | Consent Order |
| CO | Conscientious Objector |
| CO | Corporación (Spanish) |
| CO | Certifying Officer |
| CO | Combined Operations (gaming) |
| CO | Clerical Officer (obsolete, now AO) |
| CO | Collection Officer |
| CO | Clothes Optional |
| CO | Champions Online (game) |
| CO | Constant Observation (medical care) |
| CO | Command Output |
| CO | Circle Officer (India) |
| CO | Core Operation(s) |
| CO | Clinical Officer (hospital) |
| CO | Command Operations |
| CO | Commitment to Perform (common feature; Capability Maturity Model Integration) |
| CO | Chief Operator |
| CO | Consoleone (Novell GUI) |
| CO | Cargo Oil |
| CO | Combinatorics and Optimization (field of pure mathematics) |
| CO | Contracting Official |
| CO | Convert Out |
| CO | Consumer Ombudsman (UK) |
| CO | Conservation Operations |
| CO | Conseiller d'Orientation (French) |
| CO | Case Operations |
| CO | Certified Orthotist (ABC) |
| CO | Columbia Orchestra (Ellicott City, MD) |
| CO | Comitissa (Latin: Countess, Codices And Manuscripts) |
| CO | Custodial Officer |
| CO | Constraint Oriented |
| CO | Chosen Overseer |
| CO | Coastal Chart |
| CO | Circuit Overseer (Jehovah's Witnesses) |
| CO | Caucasian Ovtcharka (dog breed) |
| CO | Command Outpost |
| CO | Captive Office (Nortel) |
| CO | Consolidated Obligation |
| CO | Air Post Official (Scott Catalogue prefix; philately) |
| CO | Ciceronian Oration |
| CO | Combat Aptitude Area |
| CO | Congregation of the Oratory, Oratorians (religious order) |
| CO | Comercializadora de Occidente SA (Guatemala) |