cross-breed vs intercross

cross-breed

verb
  • To breed separate strains of the same species in order to create new traits. 

  • To breed members of similar albeit distinct species, for example, horse X donkey = mule 

noun
  • An offspring produced by cross-breeding. 

adj
  • Of or pertaining to the offspring produced by cross-breeding. 

intercross

verb
  • To breed two strains having a common ancestry with one another 

  • To cross back over one another 

noun
  • The act or product of intercrossing 

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