cooker vs double boiler

cooker

noun
  • A device for heating food, a stove. 

  • A person who is cooked; a crazy person. 

  • A person who makes or uses illicit drugs, especially methamphetamine or cannabis. 

  • An appliance or utensil for cooking food. 

  • A cooking apple. 

double boiler

noun
  • A large pan containing hot water, into which other smaller pans are set in order to cook food at low heat (below the boiling point) or to keep food warm. 

  • A pair of interlocking pots, the lower one filled with water which when boiling heats the contents of the upper pot. 

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