fuel

[fyoo-uhl]

noun

1. combustible matter used to maintain fire, as coal, wood, oil, or gas, in order to create heat or power.

2. something that gives nourishment; food.

3. an energy source for engines, power plants, or reactors.

   Kerosene is used as jet engine fuel.

4. something that sustains or encourages; stimulant.

   Our discussion provided him with fuel for debate.

   Synonyms: stimulus, impetus, sustenance, ammunition

verb (used with object)

fueled, fueling , fuelled, fuelling .

1. to supply with fuel.

verb (used without object)

fueled, fueling , fuelled, fuelling .

1. to obtain or replenish fuel.

fuel

/ fjʊəl /

noun

1. any substance burned as a source of heat or power, such as coal or petrol

2. 1. the material, containing a fissile substance, such as uranium-235, that produces energy in a nuclear reactor

   2. a substance that releases energy in a fusion reactor

3. something that nourishes or builds up emotion, action, etc

verb

1. to supply with or receive fuel

fuel

1. A substance that produces useful energy when it undergoes a chemical or nuclear reaction. Fuel such as coal, wood, oil, or gas provides energy when burned. Compounds in the body such as glucose are broken down into simpler compounds to provide energy for metabolic processes. Some radioactive substances, such as plutonium and tritium, provide energy by undergoing nuclear fission or fusion.

Other Word Forms

• fueler noun
• defuel verb (used with object)
• nonfuel adjective
• unfueled adjective
• well-fueled adjective
• fueller noun

Word History and Origins

Origin of fuel¹

First recorded in 1300–50; Middle English feuel, fuel(le), from Old French feuaile, from Vulgar Latin focālia (unrecorded), neuter plural of focālis (unrecorded) “of the hearth, fuel,” from Latin focus “hearth” ( focus ) + -ālis -al ¹

Word History and Origins

Origin of fuel¹

C14: from Old French feuaile , from feu fire, ultimately from Latin focus fireplace, hearth

Idioms and Phrases

see add fuel to the fire.

Example Sentences

MXenes are low-dimensional compounds capable of converting components from the air into ammonia that can be used in fertilizers and transportation fuels.

Read more on Science Daily

“With that effect fading, the crude oil market loses one of the supports that had fueled expectations of tighter supply.”

Read more on The Wall Street Journal

When stars like the Sun exhaust their hydrogen fuel, they begin to cool and expand, transforming into red giants.

Read more on Science Daily

Smith’s sales also come amid a marketwide about-face on AI, fueled by concerns that hyperscalers—the owners of massive data centers—are expending too much capital in exchange for little, if any, return.

Read more on Barron's

Expectations of Federal Reserve interest rate cuts in 2025 and increased demand from central banks and investors fueled gold’s rally.

Read more on Barron's

Related Words

• ammunition 
• electricity 
• food 
• gas 
• material