energy

energy — noun

1. the natural strength in your body and mind that lets you stay active, do things,

1.nounA2
Definition

the natural strength in your body and mind that lets you stay active, do things, and avoid getting tired too quickly.

Example

After a good night's sleep, Felipe woke up feeling full of energy.

full of energy — having a lot of strength

Rania put all her energy into training for the marathon.

put + all [possessive] energy into [activity]

Common collocations
  • have energy
  • full of energy
  • lack energy
  • drain someone's energy
  • put energy into
  • burst of energy
Synonyms
  • vitality

    more formal, often suggests liveliness and a zest for life; 'energy' is more about capacity to act

  • vigor

    suggests physical strength and robust health, slightly more formal than 'energy'

  • stamina

    the ability to keep going over a long period, not the same as momentary energy

Antonyms
  • fatigue

    the feeling of being worn out, the opposite of having energy

  • lethargy

    a state of laziness or lack of energy, more negative in tone

Grammar Patterns

have / lack / need + energy

full of + energy

put / pour + energy + into + [noun/gerund]

Usage Note

Common with quantifiers like 'lots of', 'so much', 'no', or 'enough'. The collocation 'put energy into' always requires a target activity after 'into'.

Common Mistakes

I have many energies today.
I have a lot of energy today.
Energy is uncountable in this sense and cannot take a plural -s.

2. the determination, enthusiasm, and effort that you choose to put into achieving

2.nounB2
Definition

the determination, enthusiasm, and effort that you choose to put into achieving something difficult or important.

Example

The team's energy carried them through the final ten minutes of the match.

[team/group]'s energy — collective determination

Eliska directed all her energy into building a small online business.

direct / channel + energy into [goal]

Common collocations
  • direct energy into
  • channel energy toward
  • with energy and determination
  • take energy to do something
Synonyms
  • drive

    emphasises strong internal motivation to achieve; 'energy' can be directed externally

  • enthusiasm

    focuses on eager enjoyment rather than sustained effort

  • determination

    emphasises firmness of purpose; 'energy' adds the idea of active effort

Antonyms
  • apathy

    lack of interest or motivation, the direct opposite of putting in effort

Grammar Patterns

direct / channel / focus + energy + into/toward + [goal]

with + energy + [verb]

take / require + energy + to-infinitive

Usage Note

Frequently appears with verbs of direction: 'direct', 'channel', 'focus', or 'put' followed by 'into' or 'toward'. Unlike sense 1 (PERSONAL VIGOR), this sense emphasises deliberate application of effort toward a specific outcome rather than general physical capacity.

Common Mistakes

She studied with a lot of energies.
She studied with a lot of energy.
Even when describing drive or effort, energy remains uncountable.

3. power that comes from resources like electricity, oil, or gas and is used to run

3.nounB1
Definition

power that comes from resources like electricity, oil, or gas and is used to run machines, provide light, or heat buildings.

Example

Sahil's house runs entirely on solar energy from panels on the roof.

solar / wind / renewable energy — source modifier

The government is investing more money in clean energy sources like wind power.

Common collocations
  • solar energy
  • wind energy
  • renewable energy
  • save energy
  • generate energy
  • clean energy
  • energy bill
  • energy source
Synonyms
  • power

    broader term that can refer to electricity or force; 'energy' is more specific to natural resources

  • fuel

    refers to the material burned for energy (coal, gas, oil), not the usable power itself

Grammar Patterns

[source] + energy

save / conserve / generate / produce + energy

energy + from + [source]

energy + bill / company / supply

Usage Note

Commonly modified by a source noun: 'solar energy', 'wind energy', 'nuclear energy', 'renewable energy'. Used with verbs such as 'save', 'conserve', 'produce', 'generate', and 'consume'. In Taiwan, 'energy' often appears in compounds like 'energy policy' (能源政策) and 'energy saving' (節能).

Common Mistakes

The energies bill is too high this month.
The energy bill is too high this month.
Energy is uncountable; do not add -s.

4. the distinctive mood or emotional quality that a person, group, or place gives o

4.nounB2
Definition

the distinctive mood or emotional quality that a person, group, or place gives off without using words.

Example

There was a strange energy in the room after the argument ended.

The old town has a creative energy that attracts artists and musicians.

a [adjective] energy — describing atmosphere

Common collocations
  • positive energy
  • negative energy
  • creative energy
  • good energy
  • bad energy
  • tense energy
  • feel the energy
Synonyms
  • atmosphere

    more neutral and formal than 'energy'; describes the general character of a place

  • vibe

    informal synonym for 'energy'; common in casual conversation

  • aura

    suggests a somewhat mystical quality, more figurative than 'energy'

Grammar Patterns

[adjective] + energy

energy + of + [place/person]

feel / sense + energy

Usage Note

Subject is typically a place (room, city, office) or a person's character. Almost always paired with an adjective that specifies the quality of the atmosphere ('positive energy', 'bad energy', 'creative energy', 'tense energy'). More common in informal or conversational English than in formal writing.

Common Mistakes

The room had a strange energies.
The room had a strange energy.
Uncountable; no plural form even in this abstract sense.

5. a scientific quantity that measures how much work matter or radiation can perfor

5.nounC1
Definition

a scientific quantity that measures how much work matter or radiation can perform, with standard units such as joules or calories.

Example

In physics class, the students learned how to calculate kinetic energy.

kinetic / potential / thermal energy — scientific types

In the school lab, Zahra watched the swinging pendulum change kinetic energy into potential energy.

kinetic / potential energy — energy transformation in a physical system

Common collocations
  • kinetic energy
  • potential energy
  • thermal energy
  • conservation of energy
  • energy transfer
  • form of energy

Grammar Patterns

[type] + energy

energy is + [verb] + [property]

conservation of + energy

energy + [verb] + from/to

Usage Note

A formal technical term in physics. Common collocations: 'kinetic energy', 'potential energy', 'thermal energy', 'chemical energy', 'conservation of energy'. The law of conservation of energy is a fundamental principle stating that energy changes form but is never lost.

Common Mistakes

Kinetic energies is a basic concept in physics.
Kinetic energy is a basic concept in physics.
Even for specific types of energy, the noun is usually uncountable.
Idioms

a ball of energy

idiom

a person who is continuously lively, active, and enthusiastic.

The new intern is a ball of energy and always runs from one task to the next.

Even after a twelve-hour shift, the nurse was a ball of energy in the ward.

a ball of energy/fire

idiom

A person who is very active and enthusiastic.

Little Maya is a ball of energy, always running and laughing.

After his coffee, Brian becomes a ball of fire at work.

Word family

Synonym discussion

Sense: noun/1

All three words relate to having physical or mental strength, but they highlight different aspects. Energy is the broadest and most common term — it covers the general capacity to be active, from waking up refreshed to powering through a workout. Vitality adds a sense of liveliness and zest for life; someone described as having 'vitality' seems to glow with health and enthusiasm. Vigor emphasises robust physical force and is slightly more formal — a vigorous handshake or a vigorous debate. Stamina is about endurance rather than intensity; it measures how long you can keep going, not how strong you feel at the start. For example: 'Felipe had the energy to run five kilometres' (general capacity), 'Tariro's vitality made her the life of the party' (liveliness), 'Eliska defended her argument with vigor' (force), and 'The marathon tests your stamina, not your speed' (endurance).

vitalityvigorstamina

Common collocations

Nouns

  • source of energy
  • amount of energy
  • level of energy
  • lack of energy
  • form of energy
  • burst of energy
  • waste of energy

Adverbs

Phrases

  • full of energy
  • with all one's energy
  • an energy crisis
  • energy levels

Prepositions

Etymology

GreekLatinFrenchEnglish

The word 'energy' comes from the ancient Greek 'energeia' (ἐνέργεια), which combines 'en' (in) and 'ergon' (work), so it originally meant 'being at work' or 'activity'. The Greek philosopher Aristotle used it to describe something that is actually happening rather than just possible. Latin borrowed it as 'energia', and French passed it into English as 'energy' in the late 1500s. For most of its early history, it described forcefulness in speech or writing. The modern scientific meaning — the capacity to do measurable work — developed in the 19th century alongside the laws of thermodynamics.