not feeling or showing gratitude; "ungrateful heirs"; "How sharper than a serpent's tooth it is / To have a thankless child!"- Shakespeare disagreeable; "I will not perform the ungrateful task of comparing cases of failure"- Abraham Lincoln
disapproval If you describe someone as ungrateful, you are criticizing them for not showing thanks or for being unkind to someone who has helped them or done them a favour. I thought it was rather ungrateful You ungrateful brat. grateful. not expressing thanks for something that someone has given to you or done for you