Noun

1. (physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs
2. Forceful exertion
3. Enterprising or ambitious drive
4. An imaginative lively style (especially style of writing)
5. A healthy capacity for vigorous activity
6. Any source of usable power
7. The federal department responsible for maintaining a national energy policy of the united states; created in 1977