altered vs retained

altered

adj
  • Neutered; having had testicles or uterus and ovaries removed to prevent procreation. 

  • Having been changed from an original form. 

noun
  • A kind of car in drag racing, usually with a partial body situated behind the exposed engine. 

retained

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