Coal (noun)

1. A black mineral found in rock strata and used as a fuel, a source of carbon, and in the production of steel and other materials.
2. A piece of coal used as fuel.

Origin:

Old english cāl, of germanic origin; related to dutch kool and german kohle.

Examples:

1. Coal is a fossil fuel.
2. Coal was once the main source of energy for industrial societies.
3. The coal miner extracted coal from the mine.
4. Coal is still used to generate electricity in many countries.
5. He placed a coal on the fire to keep it burning.