combustion vs ignition

combustion

noun
  • The act or process of burning. 

  • A process wherein a fuel is combined with oxygen, usually at high temperature, releasing heat. 

  • A process whereby two chemicals are combined to produce heat. 

  • Violent agitation, tumult. 

ignition

noun
  • The act of igniting. 

  • The phenomenon of a thermonuclear fusion reaction becoming self-sustaining and no longer requiring external heating. 

  • The initiation of combustion. 

  • A system for activating combustion in a combustion engine. 

  • Receptacle for a key used to start the engine in a vehicle. 

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