energy (n.) Look up energy at Dictionary.com
1590s, "force of expression," from Middle French énergie (16c.), from Late Latin energia, from Greek energeia "activity, operation," from energos "active, working," from en "at" (see en- (2)) + ergon "work, that which is wrought; business; action" (see organ).

Used by Aristotle with a sense of "force of expression;" broader meaning of "power" is first recorded in English 1660s. Scientific use is from 1807. Energy crisis first attested 1970.