defender vs mainstay

defender

noun
  • Someone who defends people or property. 

  • A defendant in a civil action. 

  • A fighter who seeks to repel an attack. 

  • A lawyer who represents defendants, especially a public defender; a defense attorney (US) or defence counsel (UK). 

  • One of the players whose primary task is to prevent the opposition from scoring. 

mainstay

noun
  • Someone or something that can be depended on to make a regular contribution. 

  • A stabilising rope from the top of the mainmast to the bottom of the foremast. 

  • A chief support. 

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