cool down vs defrost

cool down

verb
  • To cause (something) to become cooler; to reduce the temperature of. 

  • To become cooler; to be reduced in temperature. 

  • To become less agitated or excited. 

  • To decrease in degree or intensity. 

  • To cause (someone) to become less agitated or excited. 

defrost

verb
  • To thaw something. 

  • To recover from something tiresome. 

  • To remove frost from. 

noun
  • The removal of frost. 

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