Is it ensure, insure, or assure?
"strike repeatedly, beat violently and rapidly," early 14c., from Old French batre "to beat, strike" (11c., Modern French battre "to beat, to strike"), from Latin battuere "to beat, strike," an old word in Latin, but almost certainly borrowed from Gaulish, from PIE root *bhau- "to strike" (cf. Welsh bathu "beat;" Old English beadu "battle," beatan "to beat," bytl "hammer, mallet"). Began to be widely used 1962 in reference to domestic abuse. Related: Battered; battering. Battering-ram is an ancient weapon (Latin aries), but the word attested only from 1610s.
"flour, eggs, and milk beaten together," late 14c., from Old French batteure "a beating," from Latin battuere "to beat, knock" (see batter (v.)).