combat vs rivalry

combat

noun
  • a struggle for victory 

  • A battle, a fight (often one in which weapons are used). 

verb
  • To fight; to struggle against. 

  • To fight (with); to struggle for victory (against). 

rivalry

noun
  • An ongoing relationship between (usually two) rivals who compete for superiority. 

  • The characteristic of being a rivalrous good, such that it can be consumed or used by only one person at a time. 

  • Any competition between two or more things or factors. 

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