a. | 1. | Not acknowledging favors; not expressing thankfulness; unthankful; ungrateful. |
2. | Not obtaining or deserving thanks; unacceptable; |
Adj. | 1. | thankless - not feeling or showing gratitude; "ungrateful heirs"; "How sharper than a serpent's tooth it is / To have a thankless child!"- Shakespeare Synonyms: ungrateful, unthankful |
2. | thankless - not likely to be rewarded; "grading papers is a thankless task" Synonyms: unappreciated, ungratifying |