ETYM Old Fren. fouail, fuail, or fouaille, fuaille, Late Lat. focalium, focale, from Latin focus hearth, fireplace, in Late Lat., fire. Related to Focus.
A substance that can be burned to provide heat or power; SYN. combustible, combustible material.
Any source of heat or energy, embracing the entire range of materials that burn in air (combustibles). A nuclear fuel is any material that produces energy by nuclear fission in a nuclear reactor.

1. To provide with fuel; SYN. fire.
2. To provide with fuel; as of aircraft, ships, and cars.
3. To stimulate.
4. To take in fuel, as of a ship.