A Coal

1. (uncountable) A black rock formed from prehistoric plant remains, composed largely of carbon and burned as a fuel.
2. (countable) A piece of coal used for burning (this use is less common in American English)
3. (countable) A type of coal, such as bituminous, anthracite, or lignite, and grades and varieties thereof.
4. (countable) A glowing or charred piece of coal, wood, or other solid fuel.
5. Charcoal.