encourage vs key up

encourage

verb
  • To mentally support; to motivate, give courage, hope or spirit. 

  • To spur on, strongly recommend. 

  • To foster, give help or patronage 

key up

verb
  • To raise the intensity, excitement, tension, etc., of. 

  • To produce nervous tension in. 

  • To raise the pitch of. 

  • To raise (the whole ring of an arch) off its centering, by driving in the keystone forcibly. 

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