[ en-er-jee ]
/ ˈɛn ər dʒi /
Save This Word!
See synonyms for: energy / energies on Thesaurus.com

noun, plural en·er·gies.
Smoothly step over to these common grammar mistakes that trip many people up. Good luck!
Question 1 of 7
Fill in the blank: I can’t figure out _____ gave me this gift.

Origin of energy

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


hy·per·en·er·gy, nounself-en·er·gy, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


What is energy?

Energy refers to available power or motivation to move, as in Jada found that getting enough sleep each night gave her the energy to live each day.

Energy also refers to power that is used with exertion or force, as in Monique brought energy to the team, leading them to win more games.

In physics, energy is the power or heat that is created when something moves, is burned, or is exerted. It is typically represented in two forms: potential and kinetic energy. Potential energy is power that is stored in something as it sits still or is unburned. For example, coal contains a large amount of potential energy that is released when the coal is burned. As the coal burns, that potential energy becomes kinetic energy, energy related to the particles in the system.

Energy is a common word with several other senses related to power or motivation.

Example: Darryl found out the hard way that cell phone batteries lose their energy in the cold.

Where does energy come from?

The first records of the term energy come from the late 1500s. It ultimately comes from the Greek term energeîn, meaning “to be active.” Activity can come in many forms, but almost all burn energy.

Potential and kinetic energy can be applied to humans, too. As you eat and sleep, you build up potential energy, and as you physically move, think, breathe, or perform any physical action, that energy is used kinetically. When you’re tired, you might say you’re low on energy. And when you decide to put your energies into your art, you are spending more time doing your art and, as a result, spending more of your energy on it.

Did you know … ?

What are some other forms related to energy?

  • hyperenergy (noun)
  • self-energy (noun)

What are some synonyms for energy?

What are some words that share a root or word element with energy?

What are some words that often get used in discussing energy?

How is energy used in real life?

Energy is a common word used both in the scientific sense and in other senses, particularly those related to the power we or our devices have or don’t have.


Try using energy!

Is energy used correctly in the following sentence?

When Quinn focused his energies on his school work, his grades went up.

How to use energy in a sentence

British Dictionary definitions for energy

/ (ˈɛnədʒɪ) /

noun plural -gies
intensity or vitality of action or expression; forcefulness
capacity or tendency for intense activity; vigour
vigorous or intense action; exertion
  1. the capacity of a body or system to do work
  2. 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
a source of powerSee also kinetic energy, potential energy

Word Origin for 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 ]

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.