complain vs consent

complain

verb
  • To creak or squeak, as a timber or wheel. 

  • To make a formal accusation or bring a formal charge. 

  • To express feelings of pain, dissatisfaction, or resentment. 

consent

noun
  • Voluntary agreement or permission. 

verb
  • To express willingness, to give permission. 

  • To cause to sign a consent form. 

  • To agree in opinion or sentiment; to be of the same mind; to accord; to concur. 

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