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An individual who is exceptionally active and prone to the outdoors.

My cousin is always outdoors! If he is not parasailing or dirtbiking, he is parasailing or skiing. You've heard of Extra-Terrestrials? He's an Ultra-Terrestrial!

by Tomicus March 27, 2009
A superior, non-human entity of natural or supernatural origin that is indigenous to planet Earth.
UFO's, fairies and elves are believed by some paranormal researchers to be Ultraterrestrials.
by Vincenzo1971 August 02, 2008
A being from another dimension or plane of reality
- It doesn't make any sense, how can they summon those demon-monsters from thin air in Buffy the Vampire Slayer?

- Well, I guess they are some kind of Ultraterrestrial entities that pop in from another dimension...
by RedMattis March 19, 2010