advertise vs prewarn

advertise

verb
  • To give (especially public) notice of (something); to announce publicly. 

  • To provide public information about (a product, service etc.) in order to attract public awareness and increase sales. 

  • In gin rummy, to discard a card of one's preferred suit so as to mislead the opponent into thinking you do not want it. 

  • To provide information about a person or goods and services to influence others. 

prewarn

verb
  • To warn beforehand; to forewarn. 

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