unthank
Lack or absence of thanks or thankfulness; thanklessness; unthankfulness; ill-will.
uncountable
It is always by this unthank that things are given to the observer that we pretend to have access to the truth of the word.
Where it comes from
From Middle English unthank, from Old English unþanc (“displeasure, anger, ill-will”), from Proto-Germanic *unþankaz, equivalent to un- + thank. Cognate with West Frisian ontank, Dutch ondank, German Undank, Danish utak.
Adapted from the Wiktionary entry unthank (CC BY-SA 4.0).