flagship vs head off

flagship

verb
  • To act as a flagship for. 

noun
  • The most important one out of a related group. 

  • The ship occupied by the fleet's commander (usually an admiral); it denotes this by flying his flag. 

  • The ship regarded as most important out of a group, e.g. a nation's navy or company's fleet. 

head off

verb
  • To start out. 

  • To intercept. 

  • To avoid the undesirable consequences of; prevent. 

  • To turn away from the wind. 

  • To begin moving away. 

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