Reduction
late Middle English (denoting the action of bringing back): from Old French, or from Latin reductio(n- ), from reducere ‘bring back, restore’ (see reduce). The sense development was broadly similar to that of reduce; sense 1 dates from the late 17th century.
wiktionary
From Middle English reduccion, a borrowing from Old French reducion, from Latin reductiō, reductiōnem.
etymonline
reduction (n.)
early 15c., reduccioun, "a restoring to a former state" (a sense now obsolete), also "a conquest or subjugation" (of a people, etc.), from Old French reducion (13c., Modern French réduction) and directly from Latin reductionem (nominative reductio) "a leading back, restoration," noun of action from past-participle stem of reducere (see reduce). The meaning "diminution, a lessening" is from 1670s; chemical sense of "reversion to a simpler form" is from 1660s.
