mainstay vs protector

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. 

protector

noun
  • Someone who protects or guards, by assignment or on their own initiative. 

  • A state or other subject under international law, exercising a protectorate over another subject in international law. 

  • One having the care of the kingdom during the king's minority; a regent. 

  • A device or mechanism which is designed to protect. 

  • One who prevents interference. 

  • A cardinal, from one of the more considerable Roman Catholic nations, who looks after the interests of his people at Rome; also, a cardinal who has the same relation to a college, religious order, etc. 

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