acrid vs thermal

acrid

adj
  • Causing heat and irritation. 

  • Caustic; bitter; bitterly irritating. 

  • Sharp and harsh, or bitter and not to the taste. 

thermal

adj
  • Caused or brought about by heat. 

  • Pertaining to heat or temperature. 

  • Having a rough finish by treatment with a blow-torch. 

  • Providing efficient insulation so as to keep the body warm. 

verb
  • To create a rough finish on stone by treating it with a high-temperature blow-torch. 

  • To fly an unpowered aircraft in a (thermal) column of rising air. 

noun
  • A column of rising air in the lower atmosphere created by uneven heating of Earth's surface. 

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