fuel
n. C / Un. a material like coal, gas, or oil that people burn to produce heat or power. It can also mean anything that gives energy to a person or a situation.
n. a substance consumed to produce energy through combustion or nuclear reaction. In a figurative sense, it refers to something that sustains or intensifies an emotion, activity, or process.
The car ran out of fuel on the highway.
Wood is still the primary fuel used for cooking and heating in many rural communities around the world.
The leaked documents provided fresh fuel for the ongoing debate regarding government transparency and the ethical implications of mass surveillance.
From Middle English fuayle, from Old French fouaille, feuaille (“firewood, kindling”), from feu (“fire”), from Late Latin focus (“fire”), from Latin focus (“hearth”), whence English focus. Cognate with Spanish fuego (“fire”), and Portuguese fogo (“fire”).
Uncountable when referring to the substance in general; countable when referring to specific types or varieties of energy sources.