fossil fuel consisting of carbonized vegetable matter deposited in the Carboniferous period
"The geologists drilled deep into the earth to extract coal, a fossil fuel formed from ancient plant life during the Carboniferous period."
A black rock formed from prehistoric plant remains, composed largely of carbon and burned as a fuel.
"The power plant burns coal to generate electricity for the entire city."
In plain English: Coal is a black rock made from ancient plants that people burn to make heat and electricity.
"We burned coal in the fireplace to keep warm during the winter."
Usage: Use "coal" to refer specifically to the black, combustible rock mined from the earth for heating or electricity generation. Do not use it to describe other dark substances like charcoal or peat unless you are making a specific distinction between them.
supply with coal
"The old steamship docked at the port so it could be supplied with fresh coal for its long journey across the ocean."
To take on a supply of coal (usually of steam ships).
"The captain ordered three tenders to come alongside so we could coal before heading out into the storm."
In plain English: To coal means to put fuel into a fire, usually by shoveling coal onto it.
"The heavy rain coal all over our car's paint job."
Usage: Although "coal" can technically mean to load a ship with fuel, this usage is now archaic and rarely heard in modern conversation. You should avoid using it as a verb today; instead, simply say that a vessel was loaded with coal or fueled up.
The word "coal" comes from Old English col, which traces back to a Proto-Indo-European root meaning "to burn" or "shine." It entered English through Middle English with the same spelling and meaning, referring to the combustible rock used for fuel.