thanklessness vs unthank

thanklessness

noun
  • the property of being thankless 

unthank

noun
  • Lack or absence of thanks or thankfulness; thanklessness; unthankfulness; ill-will. 

verb
  • To recant; unsay, as what has been said by way of acknowledgement. 

  • To undo or retract one's thankfulness; negate, cancel, or revoke one's thanks. 

How often have the words thanklessness and unthank occurred in a corpus of books? (source: Google Ngram Viewer )