convict vs knock on wood

convict

verb
  • To convince, persuade; to cause (someone) to believe in (something). 

  • To find guilty, as a result of legal proceedings, or (informal) in a moral sense. 

noun
  • A person convicted of a crime by a judicial body. 

  • The convict cichlid (Amatitlania nigrofasciata), also known as the zebra cichlid, a popular aquarium fish, with stripes that resemble a prison uniform. 

  • A person deported to a penal colony. 

  • A common name for the sheepshead (Archosargus probatocephalus), owing to its black and gray stripes. 

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 convict and knock on wood occurred in a corpus of books? (source: Google Ngram Viewer )