double-cross vs encourage

double-cross

verb
  • To cross twice in hybridization, as (A × B) × (C × D); for example, in commercial hybrid seed corn, A through D are classically inbreds, and their grandoffspring is the seed for sale. 

  • To betray or go back on. 

encourage

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

  • To spur on, strongly recommend. 

  • To foster, give help or patronage 

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