Main entry: thankless, ungrateful, unthankful
Definition: not feeling or showing gratitude
Usage: ungrateful heirs; How sharper than a serpent's tooth it is / To have a thankless child!- Shakespeare
Main entry: ungrateful
Definition: disagreeable
Usage: I will not perform the ungrateful task of comparing cases of failure- Abraham Lincoln
Antonyms: pleasant
Definition: affording pleasure; being in harmony with your taste or likings