Main Entry: thank·less

Pronunciation: \ˈthaŋk-ləs\

Function: adjective

Date: 15th century

1 : not likely to obtain thanks : unappreciated <a thankless task>
2 : not expressing or feeling gratitude : ungrateful <how sharper than a serpent's tooth it is to have a thankless child — Shakespeare>

— thank·less·ly adverb

— thank·less·ness noun