Co

The abbreviation Co or CO may refer to several articles in Wikipedia:

chemical symbol for Cobalt (Co)
chemical symbol for Carbon monoxide (CO)
ISO 3166-1 code for Colombia
the U.S. postal abbreviation for Colorado
IATA airline code for Continental Airlines
Company
Commanding Officer, in the military
Central office, in telecommunications and telephony
Co is the UIC classification for the railroad locomotive wheel arrangement known as 0-6-0 in the Whyte notation; a locomotive with three powered axles (and thus six wheels) in which the axles are independently powered (e.g. by separate traction motors)