ingrate
n.
"ungrateful person," 1670s, from earlier adjective meaning "unfriendly" (late 14c.) also "ungrateful, unthankful," from Latin ingratus "unpleasant," also "ungrateful," from in- "not" (see in-(1)) + gratus "pleasing, beloved, dear, agreeable" (see grace, n.). The noun meaning "ungrateful person" dates from 1670s.
〔李〕[in-=not不；grat=thankful感激的；-e→“not thankful不感激的”→]Ⅰa. ungrateful忘恩负义的→Ⅱ n. one who is ungrateful忘恩负义者