[ en-er-jee ]
See synonyms for: energyenergies on

noun,plural en·er·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.

  1. 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.

  2. an exertion of such power: She plays tennis with great energy.

  3. the habit of vigorous activity; vigor as a characteristic: Foreigners both admire and laugh at American energy.

  4. the ability to act, lead others, effect, etc., forcefully.

  5. forcefulness of expression: a writing style abounding with energy.

  6. 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

  7. any source of usable power, as fossil fuel, electricity, or solar radiation.

Origin of energy

First recorded in 1575–85; from Late Latin energīa, from Greek enérgeia “activity,” equivalent to energe- (stem of energeîn “to be active”; see en-2, work) + -ia -y3

Other words for energy

Other words from energy

  • hy·per·en·er·gy, noun
  • self-en·er·gy, noun

Words Nearby energy Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use energy in a sentence

British Dictionary definitions for energy


/ (ˈɛnədʒɪ) /

nounplural -gies
  1. intensity or vitality of action or expression; forcefulness

  2. capacity or tendency for intense activity; vigour

  1. vigorous or intense action; exertion

  2. physics

    • the capacity of a body or system to do work

    • 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): Symbol: E

  3. a source of power: See also kinetic energy, potential energy

Origin of energy

C16: from Late Latin energīa, from Greek energeia activity, from energos effective, from en- ² + ergon work

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for energy


[ ĕnər-jē ]

  1. The capacity or power to do work, such as the capacity to move an object (of a given mass) by the application of force. Energy can exist in a variety of forms, such as electrical, mechanical, chemical, thermal, or nuclear, and can be transformed from one form to another. It is measured by the amount of work done, usually in joules or watts. See also conservation of energy kinetic energy potential energy. Compare power work.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for energy


In physics, the ability to do work. Objects can have energy by virtue of their motion (kinetic energy), by virtue of their position (potential energy), or by virtue of their mass (see E = mc2).

Notes for energy

The most important property of energy is that it is conserved — that is, the total energy of an isolated system does not change with time. This is known as the law of conservation of energy. Energy can, however, change form; for example, it can be turned into mass and back again into energy.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.