"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.
