Thankless

Thank·less

Thankless

a.
  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!
  2. Not obtaining or deserving thanks; unacceptable; as, a thankless task.
    To shepherd thankless, but by thieves that love the night allowed.