bonfire vs danger signal

bonfire

noun
  • Something like a bonfire (sense 1 or 2) in heat, destructiveness, ferocity, etc. 

  • A large, controlled outdoor fire lit to celebrate something or as a signal. 

  • A fire lit outdoors to burn unwanted items; originally (historical), heretics or other offenders, or banned books; now, generally agricultural or garden waste, or rubbish. 

verb
  • To destroy (something) by, or as if by, burning on a bonfire; (more generally) to burn or set alight. 

  • To fire (pottery) using a bonfire. 

  • To make, or celebrate around, a bonfire. 

danger signal

noun
  • An indication that a potentially bad or dangerous situation could develop. 

  • A signal set at danger and showing a red light or other stop indication, which a train driver must not pass until it changes or until manually cleared past the signal by a dispatcher. 

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