energy

UK: /ˈɛnə^rdʒi/ US: /ˈɛnɚdʒi/ ,(en′ər jē)

Inflections of 'energy' (n): npl: energies

WordReference Random House Learner's Dictionary of American English © 2026

en•er•gy /ˈɛnɚdʒi/   n., pl. -gies. 

1. the capacity or power for vigorous activity:
   [uncountable] I felt such energy that I jogged three miles.
2. Often, energies. [plural] an exertion of such power;
   effort:
   She threw all her energies into the job.
3. Physics [uncountable] Physics. the capacity to do work.Symbol: E
4. Energy [uncountable] any source of usable power, as fossil fuel, nuclear fission, electricity, or solar radiation.

WordReference Random House Unabridged Dictionary of American English © 2026

en•er•gy  (en′ər jē), n., pl. -gies. 

1. the capacity for vigorous activity;
   available power:
   I eat chocolate to get quick energy.
2. an adequate or abundant amount of such power:
   I seem to have no energy these days.
3. Often, energies. a feeling of tension caused or seeming to be caused by an excess of such power:
   to work off one's energies at tennis.
4. an exertion of such power:
   She plays tennis with great energy.
5. the habit of vigorous activity;
   vigor as a characteristic:
   Foreigners both admire and laugh at American energy.
6. the ability to act, lead others, effect, etc., forcefully.
7. forcefulness of expression:
   a writing style abounding with energy.
8. Physics the capacity to do work;
   the property of a system that diminishes when the system does work on any other system, by an amount equal to the work so done;
   potential energy. Symbol: E
9. Energy any source of usable power, as fossil fuel, electricity, or solar radiation.

• Greek enérgeia activity, equivalent. to energe- (stem of energeîn to be active; see en-², work) + -ia -y³
• Late Latin energīa
• 1575–85

Synonyms

• 1. vigor, force, potency.
• 5. zeal, push.

Collins Concise English Dictionary © HarperCollins Publishers::

energy / ˈɛnədʒɪ/ noun ( -gies)

1. intensity or vitality of action or expression; forcefulness
2. capacity or tendency for intense activity; vigour
3. the capacity of a body or system to do work
4. a measure of this capacity, expressed as the work that it does in changing to some specified reference state. It is measured in joules (SI units)
5. a source of power
   See also kinetic energy, potential energy

Etymology: 16th Century: from Late Latin energīa, from Greek energeia activity, from energos effective, from en-² + ergon work