advertisement vs secret

advertisement

noun
  • A commercial solicitation designed to sell some commodity, service or similar. 

  • A public notice. 

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

  • A recommendation of a particular product, service or person. 

secret

noun
  • Private seclusion. 

  • A piece of knowledge that is hidden and intended to be kept hidden. 

  • The key or principle by which something is made clear; the knack. 

  • A form of steel skullcap. 

  • Something not understood or known. 

  • Any prayer spoken inaudibly and not aloud; especially, one of the prayers in the Tridentine Mass, immediately following the "orate, fratres", said inaudibly by the celebrant. 

adj
  • Being or kept hidden. 

verb
  • To make or keep secret. 

  • To hide secretly. 

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