enlist vs retain

enlist

verb
  • To secure; to obtain. 

  • To recruit the aid or membership of others. 

  • To enter on a list; to enroll; to register. 

  • To voluntarily join a cause or organization, especially military service. 

noun
  • One who is enlisted, usually in a military service. 

retain

verb
  • To hold secure. 

  • To employ by paying a retainer. 

  • To hold back (a pupil) instead of allowing them to advance to the next class or year. 

  • To keep in one's pay or service. 

  • To keep in possession or use. 

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