enroll vs separate

enroll

verb
  • To enlist (someone) or make (someone) a member of 

  • To enlist oneself (in something) or become a member (of something) 

  • To enter (a name, etc.) in a register, roll or list 

separate

verb
  • To cause (things or people) to be separate. 

  • To disunite from a group or mass; to disconnect. 

  • To divide (a thing) into separate parts. 

  • To divide itself into separate pieces or substances. 

adj
  • Apart from (the rest); not connected to or attached to (anything else). 

  • Not together (with); not united (to). 

noun
  • A printing of an article from a periodical as its own distinct publication and distributed independently, often with different page numbers. 

  • Anything that is sold by itself, especially articles of clothing such as blouses, skirts, jackets, and pants. 

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