calcify vs thicken

calcify

verb
  • To make something hard and stony by impregnating with calcium salts. 

  • To become hard and stony by impregnation with calcium salts. 

thicken

verb
  • To make thicker (in the sense of more viscous). 

  • To become thicker (in the sense of wider). 

  • To become thicker (in the sense of more viscous). 

  • To make thicker (in the sense of wider). 

  • To make more frequent. 

  • To strengthen; to confirm. 

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