constrain vs urge

constrain

verb
  • To force physically, by strong persuasion or pressuring; to compel; to oblige. 

  • To keep within close bounds; to confine. 

  • To reduce a result in response to limited resources. 

urge

verb
  • To press; to push; to drive; to impel; to force onward. 

  • To present in an urgent manner; to insist upon. 

  • To put mental pressure on; to ply with motives, arguments, persuasion, or importunity. 

  • To press onward or forward. 

  • To be pressing in argument; to insist; to persist. 

  • To provoke; to exasperate. 

  • To press hard upon; to follow closely. 

noun
  • A strong desire; an itch to do something. 

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