CO
CO or variants may refer to: == Chemistry == Carbon monoxide (CO), a colorless, odorless, and tasteless gas Carbonyl group, composed of a carbon atom double-bonded to an oxygen atom: C=O Cobalt, a chemical element, symbol Co == Computing and telecommunications == .co (second-level domain), the Internet second-level domain meaning "commercial" .co, the Internet country code top-level domain (ccTLD) for Colombia Commitment ordering (CO), a concurrency control technique for databases Telephone exchange, or central office (CO) == Mathematics == Cofunction, or Co, in trigonometry Cuboctahedron, a uniform polyhedron == People == Nguyễn Hữu Có (1925–2012), Vietnamese general Conrado Co (born 1940), Filipino badminton player Alfredo Co (born 1949), Filipino Sinologist Atoy Co (born 1951), Filipino actor and basketball coach Leonard Co (1953–2010), Filipino botanist Marivic Co-Pilar (born 1971), Filipino politician Nando Có (born 1973), Bissau-Guinean footballer Kenedy Có (born 1998), Bissau-Guinean footballer Samuel S. Co, Filipino politician == Places == CO postcode area, or Colchester postcode area, England Colombia, ISO 3166-1 country code CO Colorado, United States postal abbreviation CO Counties of Ireland, abbreviated Co. == Ranks and titles == C.O., post-nominal initials of members of the congregation of the Oratory of Saint Philip Neri C/O, cadet officer ranks of the Junior Reserve Officers' Training Corps Commanding officer (CO), the officer in command of a military unit Contracting Officer (CO or KO), in the U.S. government Correctional officer (CO), an officer whose duty it is to safeguard and promote the welfare of inmates Circle officer (CO), in the Indian government Conscientious objector == Transportation == Chemins de fer Orientaux (CO), a former Ottoman railway company Chesapeake and Ohio Railway (C&O or CO), a former American railroad Cobalt Air (IATA airline designator CO, 2016-2018), a Cypriot airline Continental Airlines (IATA airline designator CO, 1937-2012), an American airline == Other uses == co-, an English prefix meaning coming together Cardiac output (CO), the volume of blood being pumped by the heart per time unit Castres Olympique, a French rugby club Certificate of occupancy (CO), a legal document Certificate of origin (often abbreviated to C/O or CoO), in international trade Co (Armenian letter) Company, abbreviated co.