metonym vs parasynonym

metonym

noun
  • A word that names an object from a single characteristic of it or of a closely related object; a word used in metonymy. 

  • A concept, idea, or word used to represent, typify, or stand in for a broader set of ideas. 

parasynonym

noun
  • A word or phrase that shares similar meanings with another term in some contexts, but not all; a close synonym. 

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