cleanse vs impair

cleanse

verb
  • To remove (something seen as unpleasant) from a person, place, or thing. 

  • To free from dirt; to clean, to purify. 

  • To spiritually purify; to free from guilt or sin; to purge. 

noun
  • An act of cleansing; a purification. 

impair

verb
  • To weaken; to affect negatively; to have a diminishing effect on. 

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