Entelechy

[Pages 114–115] [H]e [Aristotle] tells us expressly, that that which we call the rational soul is […] 'separable from the body,' […] 'because it is not the entelech of any body.' […] [page 500] Wickedness is the form and entelech of all the wicked spirits: it is the difference of a name, rather than any proper difference of natures that is between the devil and wicked men.

Source: wiktionary

Act, as we have already emphasized, is also called by Aristotle an entelechy. […] [A]ct and entelechy bespeak something fulfilled, actualized perfection, or the actualized. The soul, hence, insofar as it is essence or form of the body, is the act and entelechy of the body; and in general all forms of sensible substances are act and entelechy. God, we will see, will be pure entelechy (and just as the other movent Intelligences of the celestial spheres).

Source: wiktionary

Simply put, entelechy is any process that has a beginning, middle, and end. The end or goal is the telos; it shows up as the second syllable of the word en-TEL-echy. A simple natural entelechy is the corn entelechy. A kernel of corn when planted begins an entelechy. That is, a process of growth begins as the kernel/seed sprouts roots, then a blade. The growth process continues until it reaches its telos. Its telos is the completion of the process and the resulting production of brand new kernels that look very much like the kernel that began this process. Once that telos or goal has been reached, we say that the process is complete or perfect or teleios. But then what happens? A new entelechy begins. Each of those kernels that were produced in the previous entelechy begins to sprout and produces its own entelechy. In other words, entelechies are often cyclical.

Source: wiktionary

But while these forces of chance work both in organic and in inorganic nature, there is an additional principle in organic (living) nature: an organizing principle or entelechie.

Source: wiktionary