concoction (n.)

1530s, "digestion" (a sense now obsolete), from Latin concoctionem (nominative concoctio) "digestion," noun of action from past participle stem of concoquere "to digest; to boil together, prepare; to consider well," from assimilated form of com "together" (see con-) + coquere "to cook, prepare food, ripen, digest," from PIE root *pekw- "to cook, ripen."

Meaning "that which is concocted" is by 1850, figurative; meaning "a devising, a planning, act of preparing and combining the materials of anything" is from 1823.