evaporate vs lessen

evaporate

verb
  • to give vent to; to dissipate 

  • to expel moisture from (usually by means of artificial heat), leaving the solid portion 

  • to transition from a liquid state into a gaseous state 

  • to disappear; to escape or pass off without effect 

lessen

verb
  • To make less; to diminish; to reduce. 

  • To become less. 

conj
  • unless. 

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