English Reference

Word

energy

Phoneticsen·er·gy, stress on the first syllable

US/ˈɛnɝdʒi/

UK/ˈɛnədʒi/

Definitions

01human vitality

A2 · Elementary Uncountable noun

n. the strength and power you have to do things without getting tired.

n. the capacity for vigorous activity or the exertion of power.

“I usually have more energy in the morning after a good sleep.”

“The young volunteers brought a great deal of energy to the project, completing the renovation weeks ahead of schedule.”

Antonyms

02power sources

A2 · Elementary Uncountable noun

n. power from things like oil, coal, or the sun that we use for light and heat.

n. usable power derived from physical or chemical resources, especially to provide light and heat or to work machines.

“The government is trying to use more green energy like wind and solar power.”

“The industrial sector consumes a significant percentage of the nation's total energy, leading to calls for more efficient manufacturing processes.”

Synonyms

03scientific capacity

B2 · Upper Intermediate Uncountable noun Science Academic · Technical

n. the ability of a physical system to do work.

n. the property of matter and radiation which is manifest as a capacity to perform work, such as causing motion or interaction.

“In physics, we learned that energy cannot be destroyed, only changed.”

“Kinetic energy is the energy an object possesses due to its motion, calculated as one-half of its mass times the square of its velocity.”

Synonyms

04vibe or atmosphere

B2 · Upper Intermediate Uncountable noun Informal

n. the feeling or mood that a person or place gives you.

n. the perceived emotional quality or atmosphere emanating from a person, place, or situation.

“I didn't like the energy in that room; everyone seemed very angry.”

“The team's collective energy shifted from anxiety to determination as soon as the captain delivered her pre-match speech.”

Synonyms

05gaming resource

B1 · Intermediate Uncountable noun Computing Informal

n. a limited number of points a character can use to perform actions in a game.

n. a quantifiable resource in game mechanics that limits the number of actions a player or unit can perform within a specific timeframe.

“My character ran out of energy, so I had to wait for it to refill before attacking again.”

“Players must manage their energy bars carefully, as high-damage abilities consume more resources than standard defensive maneuvers.”

Synonyms

Collocations

Common phrases and expressions where native English speakers use the word “energy” in context.

01. energy security 02. energy costs 03. energy bills 04. energy efficiency 05. energy levels 06. energy needed 07. energy prices 08. energy efficient

Real-World Examples

“Renewables will grow faster than any major energy source in the next decade, according to the world’s energy watchdog, making the transition away from fossil fuels “inevitable”, despite a green backlash in the US and parts of Europe.”
The Guardian 12 Nov 2025
“Renewable energy overtook coal as the world's leading source of electricity in the first half of this year - a historic first, according to new data from the global energy think tank Ember.”
BBC News 7 Oct 2025
“China is dominating the energy transition with astonishing results, while fossil fuel fascists in the US try to turn back the clock”
The Guardian 17 May 2026

Etymology

From Middle French énergie, from Late Latin energia, from Ancient Greek ἐνέργεια (enérgeia, “activity”), from ἐνεργός (energós, “active”), from ἐν (en, “in”) + ἔργον (érgon, “work”). The sense in physics was coined by English polymath Thomas Young in 1802 in his lectures on Natural Philosophy.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Synonyms

Antonyms

Word family

NOUN

energy(A2)

ADJECTIVE

Related words

Idioms

Domain

Physics

This entry

Exam level
CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.A2 KeyIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.3.0–4.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 2.0–2.524–43TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.225–549
Frequency
Very common
Level
A2 · ElementaryOxford
Updated

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English Reference