"Entelechy" has been defined in some slightly differing ways. I was always taught a definition similar to that described by this Wikipedia article.
You could imagine Entelechy as the work required to maintain a particular state - a state which is in some sense an end in itself. Part of it's meaning could be captured by thinking of Homeostasis - a process which works to ensure some proper or advantageous state of being is sustained (constant blood temperature etc). Entelechy could, in this sense, perhaps be contrasted/seen to fit with something like the second law of thermodynamics, which implies that things become less ordered over time unless they do some work to stay ordered by consuming some other resource. This make sense if you consider Aristotle's view of Forms, and his formal cause (which has to deal with the fact of aging both in living things and the public architecture of Athens).
But the final cause seems to be at play in the concept of Entelchy too, and so we have to think about what the final cause of the particular object in question might be (according to Aristotle). For most living things, the Final cause is to do work and produce some effect by it (if I remember correctly, there are passages where he discusses the Final cause of some wild Animals being their useful domestication by man, because that is the state in which they best fulfilled their potential for work). As a result of this sort of conception of the ultimate telos of living things, Enetlechy is the work required once you reach your telos, simply to stay at that point. Remember his view of ethics too - much like the body builder, once we've got our bulging moral muscles, we are still going to have to keep engaging in moral thought and exercise simply to maintain them at the perfect stature. We need to do this with all our "jobs" in general too.
So perhaps an easily made comparison would be with some one who "sat on their laurels". Or, more academically I guess, the question is in part about the value of expending effort to maintain an existing order. And the contrary of Entelechy? Seems to be something like in-activity. I'm not sure if it's actually possible, under Aristotle, for any living thing to be completely free of Entelechy, or for it not to posses some degree of Entelichal effort, since all beings do posses a final cause, which they are simply more or less capably able to achieve, and it is in the nature of a living thing to be active.