un·grate·ful 
(ŭn-grātfəl)
(ŭn-grātfəl)adj.
1. Not feeling or exhibiting gratitude, thanks, or appreciation.
2. Not agreeable or pleasant; repellent: "I will not perform the ungrateful task of comparing cases of failure" (Abraham Lincoln).
un·grateful·ly adv.
un·grateful·ness n.