Definition of: energy

(en′ər·jē) noun plural ·gies
1. The power by which anything acts effectively to move or change other things or accomplish any result.
2. Habitual tendency to and readiness for effective action.
3. Power in active exercise; force in operation.
4. Physics The capacity of doing work and of overcoming inertia, as by heat, light, radiation, or mechanical and chemical forces. Potential energy is that due to the position of one body relative to another; kinetic energy is manifested by bodies in motion. The units of energy and work are mutually convertible, and energy itself is regarded as functionally related to the mass and velocity of a material system. See QUANTUM.
5. Vigor and forcefulness of style or expression. See synonyms under POWER, WARMTH. [<LL energia <Gk. energeia <energēs <en- on + ergon work]