CO can stand for:

• Carbon monoxide, molecular formula
• Central office, in telecommunications and telephony
• Chesapeake and Ohio Railroad
• Colombia, in various country codes
• Colorado, U.S. postal abbreviation
• Commanding officer, military
• Conscientious objector, military
• Continental Airlines, IATA airline designator
• Collaborative Browsing
• Chinese Orchestra
• Correctional Officer, Correctional Officer

Co can stand for: Carbon monoxide, chemical formula CO, is a colorless, odorless, tasteless, flammable and highly toxic gas. ... In the field of telecommunications, a central office or telephone exchange houses equipment that is commonly known as simply a switch, which is a piece of equipment that connects phone calls. ... The Chesapeake and Ohio Railway (C&O) was a Class I railroad formed in 1869 in Virginia from many smaller railroads begun in the 19th century. ... Official language(s) English Capital Denver Largest city Denver Area  - Total   - Width   - Length    - % water  - Latitude  - Longitude Ranked 8th 104,185 sq mi  269 837 km² 280 miles  451 km 380 miles  612 km 0. ... In military organizations, the commanding officer (CO) is the officer in command of a military unit. ... A conscientious objector is an individual whose personal beliefs are incompatible with military service, perhaps with any role in the armed forces or just with a particular war. ... Continental Airlines (IATA: CO, ICAO: COA, and Callsign: Continental) (NYSE: CAL) is an American airline. ... Chinese orchestra can refer to: Ancient Chinese orchestras Modern large Chinese orchestras // Ancient Chinese orchestras According to recent archaeological findings, ancient Chinese music was much more developed and sophisticated than is generally believed. ... A prison officer is a person charged with the responsibility of the supervision of prisoners in a prison. ...

• Cobalt, a ferromagnetic metallic chemical element
• Company (law) (Co.), a general business abbreviation
• Co (ethnicity), an ethnic group in Southeast Asia
• Cowling number, in physics

co can stand for: General Name, Symbol, Number cobalt, Co, 27 Chemical series transition metals Group, Period, Block 9, 4, d Appearance metallic with gray tinge Atomic mass 58. ... A company is, in general, any group of persons, which are known as its members, united to pursue a common interest. ...

• "check out", Revision Control System command

.co can stand for: The Revision Control System (RCS) is a software implementation of revision control that automates the storing, retrieval, logging, identification, and merging of revisions. ...

• .co, the Internet second-level domain within other country code domains

c/o can stand for: .co is the Internet country code top-level domain (ccTLD) for Colombia. ...

• "Care of", used to address a letter when the letter must pass through an intermediary