feedforward vs harbinger

feedforward

verb
  • To respond in advance 

noun
  • An anticipatory response to expected changes in the environment of a system 

harbinger

verb
  • To announce or precede; to be a harbinger of. 

noun
  • A person or thing that foreshadows or foretells the coming of someone or something. 

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