reliever vs stoker

reliever

noun
  • Something which relieves (pain, etc.). 

  • A relief pitcher. 

  • Someone who fills in for another. 

stoker

noun
  • A device for stoking a fire; a poker. 

  • A person who stokes, especially one on a steamship or steam train, who stokes coal in the boilers. 

  • A person who pedals on the back of a tandem bicycle. 

  • A device that feeds coal into a furnace, etc., automatically. 

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