Origin and history of eaten

Middle English eten, from Old English etan (class V strong verb; past tense æt, past participle eten) "consume food; devour, consume," from Proto-Germanic *etan (source also of Old Frisian ita, Old Saxon etan, Middle Dutch eten, Dutch eten, Old High German ezzan, German essen, Old Norse eta, Gothic itan), from PIE root *ed- "to eat."

The transferred sense of "corrode, wear away, consume, waste" is from 1550s. The meaning "to preoccupy, engross" (as in what's eating you?) is recorded by 1893. The slang sexual sense of "do cunnilingus on" is recorded by 1927.

Slang phrase eat one's words "retract, take back what one has uttered" is from 1570s; to eat one's heart out is from 1590s; for eat one's hat, see hat. Eat-in (adj.) in reference to kitchens is from 1955, from the verbal phrase. To eat out "dine away from home" is from 1930.

"not consumed," c. 1300, from un- (1) "not" + eaten.