fiction vs opus

fiction

noun
  • Literary type using invented or imaginative writing, instead of real facts, usually written as prose. 

  • A verbal or written account that is not based on actual events (often intended to mislead). 

  • A legal fiction. 

opus

noun
  • A work, especially of art. 

  • A work of music or set of works with a specified rank in an ordering of a composer's complete published works. 

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