Etymology
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actuality (n.)

late 14c., "power, efficacy," from Medieval Latin actualitatem (nominative actualitas), from Late Latin actualis "pertaining to action," from Latin actus "a doing" (from PIE root *ag- "to drive, draw out or forth, move"). A Latin loan-translation of Greek energeia "activity, action, operation" (see energy). Meaning "state of being real" is from 1670s (actualities "existing conditions" is from 1660s).

Mod. use of actuality in the sense of realism, contact with the contemporary, is due to Fr. actualité, from actuel, which does not mean actual, real, but now existing, up to date. [Weekley]
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entelechy (n.)

c. 1600, from Latinized form of Greek entelekheia "actuality," from en "in" (see en- (2)) + telei, dative of telos "perfection" (see telos) + ekhein "to have" (from PIE root *segh- "to hold"). In Aristotle, "the condition in which a potentiality has become an actuality."

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energy (n.)

1590s, "force of expression," from French énergie (16c.), from Late Latin energia, from Greek energeia "activity, action, operation," from energos "active, working," from en "at" (see en- (2)) + -ergos "that works," from ergon "work, that which is wrought; business; action" (from PIE root *werg- "to do").

Used by Aristotle with a sense of "actuality, reality, existence" (opposed to "potential") but this was misunderstood in Late Latin and afterward as "force of expression," as the power which calls up realistic mental pictures. Broader meaning of "power" in English is first recorded 1660s. Scientific use is from 1807. Energy crisis first attested 1970.

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