lavage vs water down

lavage

verb
  • To wash a hollow organ 

noun
  • A washing. 

  • A washing of a hollow organ. 

water down

verb
  • To dilute; to add water to. 

  • To simplify or oversimplify; to make easier; to make less difficult. 

  • To make weaker, less effective. 

  • To make less restrictive; to make more lenient. 

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