Energy

Part of speech: noun (n.)

1. Internal or inherent power; capacity of acting, operating, or producing an effect, whether exerted or not; as, men possessing energies may suffer them to lie inactive. The great energies of nature are known to us only by their effects. Paley.

2. Power efficiently and forcibly exerted; vigorous or effectual operation; as, the energy of a magistrate.

3. Strength of expression; force of utterance; power to impress the mind and arouse the feelings; life; spirit; -- said of speech, language, words, style; as, a style full of energy.

4. Capacity for performing work.

Synonyms: Force; power; potency; vigor; strength; spirit; efficiency; resolution.