batter (n.1)
in cookery, "a mixture of ingredients (flour, eggs, milk) beaten together," late 14c., from Old French batteure "a beating," from Latin battuere "to beat, knock" (see batter (v.)).
batter (n.2)
"one who strikes or beats with a bat," 1773, agent noun from bat (v.2). Earlier noun was batsman (1756).
batter (v.)
"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, batuere "to beat, strike," a rare word in literary Latin but evidently an old one and popular in Vulgar Latin. Probably borrowed from Gaulish (compare Welsh bathu "beat," Irish and Gaelic bat, bata "staff, cudgel") and perhaps from PIE root *bhau- "to strike." (source also of Welsh bathu "beat;" Old English beadu "battle," beatan "to beat," bytl "hammer, mallet").

The word began to be widely used in reference to domestic abuse in 1962. Related: Battered; battering. Battering-ram is an ancient weapon (Latin aries), but the phrase is attested only from 1610s.