enlist vs round up

enlist

verb
  • To recruit the aid or membership of others. 

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

  • To secure; to obtain. 

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

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

round up

verb
  • To collect or gather (something) together. 

  • To gather (cattle) together by riding around them. 

  • To round (a number) to the smallest integer that is not less than it, or to some other greater value, especially a whole number of hundreds, thousands, etc. 

  • To arrest or detain a group of people without individualized suspicion or cause, often as a form of targeted persecution. 

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