Digital Companion to C. S. Peirce
1904 | Sketch of Dichotomic Mathematics | NEM 4:300

…I call the sign the Entelechy, or perfectionment, of reality.

1904 [c.] | New Elements (Kaina stoiceia) | EP 2:304

The purpose of every sign is to express “fact,” and by being joined with other signs, to approach as nearly as possible to determining an interpretant which would be the perfect Truth, the absolute Truth, and as such (at least, we may use this language) would be the very Universe. Aristotle gropes for a conception of perfection, or entelechy, which he never succeeds in making clear. We may adopt the word to mean the very fact, that is, the ideal sign which should be quite perfect, and so identical, – in such identity as a sign may have, – with the very matter denoted united with the very form signified by it. The entelechy of the Universe of being, then, the Universe qua fact, will be that Universe in its aspect as a sign, the “Truth” of being. The “Truth,” the fact that is not abstracted but complete, is the ultimate interpretant of every sign.

1907 | The Fourth Curiosity | CP 6.341

The mode of being of the composition of thought, which is always of the nature of the attribution of a predicate to a subject, is the living intelligence which is the creator of all intelligible reality, as well as of the knowledge of such reality. It is the entelechy, or perfection of being.