1530s, "digestion," from Latin concoctionem (nominative concoctio) "digestion," noun of action from past participle stem of concoquere (see concoct). Meaning "preparation of a medicinal potion" is from 1851; sense of "a made-up story" is from 1823.[concoction etymology, concoction origin, 英语词源]
late 14c., from French décoction (13c.) or directly from Latin decoctionem (nominative decoctio) "a boiling down," noun of action from past participle stem of decoquere "to boil down," from de- "down" (see de-) + coquere "to cook" (see cook (n.)).