cinder vs culm

cinder

noun
  • Partially or mostly burnt material that results from incomplete combustion of coal or wood etc. 

  • An ember. 

  • Slag from a metal furnace. 

verb
  • To cover with cinders. 

  • To reduce to cinders. 

culm

noun
  • waste coal, used as a poor quality fuel; slack. 

  • the stem of a plant, especially of grass or sedge 

  • anthracite, especially when found in small masses 

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