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

“Put some coal on the fire.”

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

“Put some coals on the fire.”

A type of coal, such as bituminous, anthracite, or lignite, and grades and varieties thereof.

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

To supply with coal.

“to coal a steamer”

To be converted to charcoal.