becalm vs cool off

becalm

verb
  • To deprive (a ship) of wind, so that it cannot move (usually in passive). 

cool off

verb
  • To decrease in temperature, activity, or temper. 

  • To cause to decrease in temperature, activity or temper. 

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