coal [ koul ] noun ***
uncount a hard black substance that is dug from the ground and burned as fuel to provide heat:
Put some more coal on the fire.
coal dust
a piece/lump of coal
a. uncount used for talking about the industry of digging coal out of the ground:
Is there a future for coal?
the coal industry
b. count a piece of coal, especially when it is burning:
Nina stirred the coals with the poker.
rake/haul someone over the coals
to speak angrily to someone because they have done something wrong

Usage of the words and phrases in modern English. 2013.