c. 1400, coagulacioun, "act of changing from a fluid to a thickened state," from Latin coagulationem (nominative coagulatio), noun of action from past participle stem of coagulare "cause to curdle" (see coagulate). Meaning "mass or quantity of coagulated matter" is from 1660s.
co-act
coadaptation
coadjacent
coagulant
coagulate
coagulation
coal
coal-black
coalesce
coalition
coal-miner