c o

one who refuses to serve in the military due to personal or religious beliefs

In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom : C=O. The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e.g. nickel carbonyl); in this situation, carbon is triple-bonded to oxygen : C≡O. The remainder of this article concerns itself with the organic chemistry definition of carbonyl.
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Abbreviation for central office.

A common carrier switching center in which trunks and loops are terminated and switched. Note: In the DOD, "common carrier" is called "commercial carrier." Synonyms exchange, local central office, local exchange, local office, switching center (except in DOD DSN [formerly AUTOVON] usage), switching exchange, telephone exchange. Deprecated synonym switch.