mainstay vs safeguard

mainstay

noun
  • A chief support. 

  • 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. 

safeguard

noun
  • One who, or that which, defends or protects; defence; protection. 

  • A safe-conduct or passport, especially in time of war. 

  • Something that serves as a guard or protection; a defense. 

verb
  • To escort safely. 

  • To implement safeguarding. 

  • To protect, to keep safe. 

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