noun

energy

The capacity to do work or cause change, including the strength to act.

After a good night's sleep, she has energy to exercise.

Etymology

The Greek word names activity or operation. Its modern physical use focuses on the capacity for such activity, while ordinary speech applies that capacity to personal vigor.

More examples

  • Solar panels convert sunlight into electrical energy.
  • The battery stores enough energy to power the flashlight.
  • He directs his energies toward helping his neighbors.

Forms

energy · energies

energetic adjective — Full of energy and enthusiasm.

energetically adverb — With great energy and enthusiasm.

Similar words

power
In physics, measures how quickly energy is transferred or used.
strength
Emphasizes physical force rather than the broader capacity for activity.
vitality
Emphasizes lively health and vigor in living things.