forehold vs knock on wood

forehold

verb
  • To hold or believe (something) beforehand; to assume; to anticipate, to predict. 

noun
  • The forward or front part of the hold of a ship. 

knock on wood

verb
  • To take a customary action to ward off some misfortune that is believed to be attracted by a presumptuous statement. 

intj
  • Hopefully; a self-directive to undertake the customary action to ward off bad luck. 

How often have the words forehold and knock on wood occurred in a corpus of books? (source: Google Ngram Viewer )