feedforward vs forespell

feedforward

verb
  • To respond in advance 

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

forespell

verb
  • To spell in advance; foretell; make a warning about something upcoming; tell or indicate beforehand; predict 

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