General English

  • noun the force or strength of a person
  • noun a power which makes something work

General Science

  • noun electricity or other fuel




  • noun power produced from electricity, petrol or a similar source

Cars & Driving

  • noun the capacity for doing work, measured in joules or in the case of electrical energy, in kilowatt-hours


  • The capacity to do work. Energy cannot be created nor destroyed in an isolated system, but it can be changed from one form to another. Forms of energy include electrical, chemical, acoustic, atomic, and solar. Usually expressed in joules, but other units may be utilized, such as ergs, calories, or watt-hours.
  • symbolE

Origin & History of “energy”

Energy comes ultimately from Greek érgon ‘deed, work’. this was a descendant of Indo-European *wergon, which also produced English work, liturgy, organ, and orgy. Addition of the prefix en- ‘at’ produced the adjective energḗs or energōs ‘at work’, hence ‘active’, which Aristotle used in his Rhetoric as the basis of a noun enérgeia, signifying a metaphor which conjured up an image of something moving or being active. This later came to mean ‘forceful expression’, or more broadly still ‘activity, operation’. English acquired the word via late Latin energīa.