distend vs lessen

distend

verb
  • To cause to swell. 

  • To extend or expand, as from internal pressure; to swell 

  • To cause gravidity. 

lessen

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

  • To become less. 

conj
  • unless. 

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