char vs coal

char

verb
  • To burn something to charcoal. 

  • To work, especially to do housework; to work by the day, without being a regularly hired servant. 

  • To burn slightly or superficially so as to affect colour. 

  • To work or hew (stone, etc.) 

noun
  • A charred substance. 

  • A charlady, a woman employed to do housework; cleaning lady. 

  • An odd job, a chore or piece of housework. 

  • A character (text element such as a letter or symbol). 

  • One of the several species of fishes of the genus Salvelinus. 

coal

verb
  • To burn to charcoal; to char. 

  • To supply with coal. 

  • To take on a supply of coal (usually of steam ships). 

  • To mark or delineate with charcoal. 

  • To be converted to charcoal. 

noun
  • A type of coal, such as bituminous, anthracite, or lignite, and grades and varieties thereof, as a fuel commodity ready to buy and burn. 

  • A glowing or charred piece of coal, wood, or other solid fuel. 

  • A black or brownish black rock formed from prehistoric plant remains, composed largely of carbon and burned as a fuel. 

  • A piece of coal used for burning (this use is less common in American English) 

  • charcoal. 

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