energy (Noun) — (physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs. ex. "energy can take a wide variety of forms"
energy (Noun) — Forceful exertion. ex. "he plays tennis with great energy"
energy (Noun) — Enterprising or ambitious drive. ex. "Europeans often laugh at American energy"
energy (Noun) — An imaginative lively style (especially style of writing). ex. "his writing conveys great energy"
energy (Noun) — A healthy capacity for vigorous activity. ex. "jogging works off my excess energy"
energy (Noun) — Any source of usable power. ex. "the DOE is responsible for maintaining the energy policy"
energy (Noun) — The federal department responsible for maintaining a national energy policy of the United States; created in 1977.