propitiation (n.)

late 14c., propiciacioun, "atonement, expiation," from Late Latin propitiationem (nominative propitiatio) "an atonement," noun of action from past-participle stem of Latin propitiare "appease, propitiate," from propitius "favorable, gracious, kind, well-disposed," from pro- "forward" (see pro-) + stem related to petere "to make for, go to; seek, strive after; ask for, beg, beseech, request" (from PIE root *pet- "to rush, to fly").

The sense in Latin is perhaps because the word originally was religious, literally "a falling or rushing toward," hence "eager," and, of the gods, "well-disposed." Earliest recorded form of the word in English is propitiatorium "the mercy seat, place of atonement" (c. 1200), translating Greek hilasterion.