Greetings all - brand new member here. I joined specifically to address this topic, which I've had a pet theory about for some time. It goes back to the definition of demon as a "possessing spirit". Based on the movie, in which a few major scenes involve attempts by Mo'at to permanently transfer consciousnesses from one body to another via the Tree of Souls, it seems the idea of soul transfer is something known to the Na'vi. And, since it seems like it is possible to "upload" one's spirit into the network, it may also be possible for a spirit to "download" itself into anyone bonded to the network as well. It may in fact be the case that malevolent, strong-willed spirits in the Pandoran network could forcible invade the body of another na'vi during tsaheylu, and this is the vrrtep.
This idea would also be consistent with the Avatars being referred to as "demons in a false body"; given the way the Avatar program works, this would in fact be a pretty accurate description from the na'vi POV.
First of all, i'd like to welcome you to this forum, ma tsmukan

. Secondly, i'd like to say that i find your theory very interesting

. I've never thought about it in that way before.
I would tend to agree with RiverBorn to a large extent. Although, I might add, we know little of Eywa's spiritual influence. In most religions, there is an opposing force, a devil, an anti good, anti God. etc. That is not introduced anywhere except in that one statement by Tsu'tey. In that statement, it is implied that a spirit (good or evil) has taken up residence where it is not welcomed. Implying also that "possession" is possible (WalkINS not welcome)

An Avatar is not born from the body of a Na'vi woman. False body could be their (Na'vi) interpretation of the science magic, that produces them. A process that would have been explained possibly, by Grace Augustine. (She had established her school for ten years.) Avatars might seems like a Frankenstein monster;
animated yet not quite Na'vi, though disquietingly similar.
Naming such a person UnilTìrantokx - Dream Walker Body - is a very poetic description. I had to see the movie a second time to confirm that these creatures were grown in test tubes, rather than being a reanimated corpse! How must it have seemed to Tsu-tey?
Having said that, VRRRTEP could be a loose translation of demon, yet not be analogous to OUR concept of evil spirits. (I just read Mary Shelley's original FRANKENSTEIN, which deals with these issues as well!)
Yeah, even animistic religions such as the Na'vi's tend to include some kind of evil forces in it.
You thought the avatars were reanimated corpses

?! Sorry if it sounds like i'm mocking you, but lol

!
I'm going to have to go back and reread this thread. Meantime, I hope I'm not going over old territory by saying that 'demon' is our translation of 'vrrtep' because that's the only thing we have as a extant referent for it.
It could be that our translation is in error, and that vrrtep has a different cultural connotation than we can understand.
As a weak example, do most of us really comprehend 'aean' the same way a Na'vi would? I cannot. Green and blue are distinctly different to me until we get into the teal shades, but even then I can 'see' a difference.
Hate to tell you, ma Seze Mune, but you
are going over old territory

. Still, i guess it doesn't hurt to say it again

.
Yep. See skxawng - so many people use that in a self-deprecating manner when it is far more of an insult than they might think, because an insistence on always giving a single-word translation does necessarily impair precision, including for languages spoken on Earth.
Since culture plays such a big part in the development of language, there'll almost always be words whose meaning can't be translated into a single word in another language, or even translated at all.