Thankless
Pronunciation : Thank"less
Part of Speech : a.
Definition : 1. Not acknowledging favors; not expressing thankfulness; unthankful; ungrateful. That she may feel How sharper than a serpent's tooth it is To have a thankless child! Shak.
2. Not obtaining or deserving thanks; unacceptable; as, a thankless task. To shepherd thankless, but by thieves that love the night allowed. Chapman. -- Thank"less*ly, adv. -- Thank"less*ness, n.
Source : Webster's Unabridged Dictionary, 1913