smouldering vs wildfire

smouldering

noun
  • The act by which something smoulders; residual heat. 

adj
  • Burning slowly, producing smoke but no flame. 

wildfire

noun
  • Something that acts or spreads quickly and uncontrollably. 

  • A rapidly spreading fire, especially one occurring in a wildland area. 

  • A spreading disease of the skin, particularly erysipelas. 

  • Greek fire, Byzantine fire. 

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