coffer?a strongbox cogent?forceful cogitate?to think over cognate?related cognizant?aware cognomen?a name cohesion?tendency to stick together cohort?a group or band; an associate coincident?happening at the same time collaborate?to work together collateral?side by side; parallel collocation?an arrangement colloquial?conversational; informal (speech) colloquy?a formal discussion or conference collusion?conspiracy colossal?huge comatose?pertaining to a coma comely?attractive comestible?edible comity?politeness commensurate?equal in size or measure comminuted?powdered commiseration?sympathy or sorrow commodious?spacious commutation?an exchange or substitution compassion?deep sympathy compatible?able to get along well together