petrify vs water down

petrify

verb
  • To make callous or obdurate; to stupefy; to paralyze; to transform; as by petrification. 

  • To produce rigidity akin to stone. 

  • To become stone, or of a stony hardness, as organic matter by calcareous deposits. 

  • To harden organic matter by permeating with water and depositing dissolved minerals. 

  • To immobilize with fright. 

  • To become stony, callous, or obdurate. 

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 petrify and water down occurred in a corpus of books? (source: Google Ngram Viewer )