unthankful

The story

1. Old English · inherited fromunþancful
2. Middle English · inherited fromunthankful
3. English todayunthankful

From Middle English unthankful, from Old English unþancful, unþancfull, unġeþancfull (“unthankful, ungrateful”), equivalent to un- + thankful. Cognate with Old High German undankfol (“unthankful, ungrateful”).