Entelechy

An interesting passage from Joe Sachs's article at the IEP, Aristotle: Motion and its Place in Nature, on Aristotle's invention of the word entelecheia:

Thus if we translate entelecheia as “completeness” or “perfection,” the contribution the meaning of exein makes to the term is not evident. Aristotle probably uses exein for two reasons which lead to the same conclusion: First, one of the common meanings of exein is “to be” in the sense of to remain, to stay, or to keep in some condition specified by a preceding adverb as in the idiomskalos exei, “things are going well,” or kakos exei, “things are going badly.” It means “to be” in the sense of to continue to be. This is only one of several possible meanings of exein, but there is a second fact which makes it likely that it is the meaning which would strike the ear of a Greek-speaking person of Aristotle’s time. There was then in ordinary use the word endelecheia, differing from Aristotle’s word entelecheia only by a delta in place of the tau. Endelecheia means continuity or persistence. As one would expect, there was a good deal of confusion in ancient times between the invented and undefined term entelecheia and the familiar word endelecheia. The use of the pun for the serious philosophic purpose of saying at once two things for whose union the language has no word was a frequent literary device of Aristotle’s teacher Plato. In this striking instance, Aristotle seems to have imitated the playful style of his teacher in constructing the most important term in his technical vocabulary. The addition of exein to enteles, through the joint action of the meaning of the suffix and the sound of the whole, superimposes upon the sense of “completeness” that of continuity.