avoid vs head off

avoid

verb
  • To stay out of the way of (something harmful). 

  • To try not to do something or to have something happen 

  • to keep away from; to keep clear of; to stay away from 

  • To try not to meet or communicate with (a person); to shun 

  • To make void, to annul; to refute (especially a contract). 

  • To defeat or evade; to invalidate. 

head off

verb
  • To avoid the undesirable consequences of; prevent. 

  • To start out. 

  • To intercept. 

  • To turn away from the wind. 

  • To begin moving away. 

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