noun, plural: energies
(1) Tthe capacity for work.
(2) The ability to do work, or produce change.
Energy exists in different forms but is neither created nor destroyed; it simply converts to another form. Examples of energy include: kinetic, potential, thermal, gravitational, elastic, electromagnetic, chemical, nuclear, and mass. Energy can be expressed in joules or ergs
In biology, energy is often stored by cells in biomolecules, like carbohydrates (sugars) and lipids. The energy is released when these molecules have been oxidized during cellular respiration. The energy released from them when they are oxidized during cellular respiration is carried and transported by an energy-carrier molecule called ATP.
Word origin: From Ancient Greek ἐνέργεια (energeia) "action, act, work", < ἐνεργός (energos) "active" < ἐν (en) "in" + ἔργον (ergon) "work".