antithesis vs antonym

antithesis

noun
  • A proposition that is the diametric opposite of some other proposition. 

  • A device by which two contrasting ideas are juxtaposed in parallel form; a figure of speech arranged in this manner 

antonym

noun
  • A word which has the opposite meaning of another word. 

  • A word that describes one end of a scale, while its opposite describes the other end, such as large versus small; a gradable antonym. 

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