condense vs thicken

condense

verb
  • To concentrate toward the essence by making more close, compact, or dense, thereby decreasing size or volume. 

  • To be transformed from a gaseous state into a liquid state. 

  • To transform from a gaseous state into a liquid state via condensation. 

thicken

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

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

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

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

  • To make more frequent. 

  • To strengthen; to confirm. 

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