Coal is a fossil fuel extracted from the ground either by underground mining, open-pit mining or strip mining. It is a readily combustible black or brownish-black sedimentary rock. It is composed primarily of carbon and hydrocarbons, along with assorted other elements, including sulfur. Often associated with the Industrial Revolution, coal remains an enormously important fuel and is the most common source of electricity world-wide. In the United States, for example, the burning of coal...
- A Roman unit of weight, 1⁄1728 of a pound.
- A weight of four grains used in weighing gold and precious stones; a carat.
- In anatomy, a formation suggesting a husk or pod.
- The lowest unit in the Roman coinage, the twenty-fourth part of a solidus.
- A coin of base silver of the Gothic and Lombard kings of Italy.