Noun

Singular coal

Plural coal or coals

coal (plural coal or coals)

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. Note that in British English the first of the following examples would usually be used, whereas in American English the latter would.

   Put some coals on the fire.

   Put some coal on the fire.

3. (countable) A type of coal, such as bituminous, anthracite, or lignite, and grades and varieties thereof.
4. (countable) A smouldering piece of material.

   Just as the camp-fire died down to just coals, with no flames to burn the marshmallows, someone dumped a whole load of wood on, so I gave up and went to bed.

Hyponyms

• anthracite, bitumin

Derived terms

• bituminous coal, soft coal
• coal ball
• coal bed
• coal black
• coalboy
• coal gas
• coal hole
• coal oil
• coal tar
• coal tit
• coalmine
• coals to Newcastle
• channel coal
• hard coal (see: anthracite)

Related terms

• colliery

Coal is a readily combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly sulfur, hydrogen, oxygen and nitrogen.

Coal begins as layers of plant matter accumulate at the bottom of a body of water. For the process to continue the plant matter must be protected from biodegradation and oxidization, usually by mud or acidic water. The wide shallow seas of the Carboniferous period provided such conditions. This trapped atmospheric carbon in the ground in immense peat bogs that eventually were covered over and deeply buried by sediments under which they metamorphosed into coal. Over time, the chemical and physical properties of the plant remains (believed to mainly have been fern-like species antedating more modern plant and tree species) were changed by geological action to create a solid material.

Coal, a fossil fuel, is the largest source of energy for the generation of electricity worldwide, as well as one of the largest worldwide anthropogenic sources of carbon dioxide emissions. Gross carbon dioxide emissions from coal usage are slightly more than those from petroleum and about double the amount from natural gas. Coal is extracted from the ground by mining, either underground or in open pits.