troglodyte

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A member of a fabulous or prehistoric race of people that lived in caves, dens, or holes.
• noun A person considered to be reclusive, reactionary, out of date, or brutish.
• noun A nonhuman ape. Not in scientific use.
• noun An animal that lives underground, as an ant or a worm. Not in scientific use.

from The Century Dictionary.

• Inhabiting caverns; cavedwelling; cavernicolous; spelæan; troglodytic: specifically noting human beings, apes, and birds.
• noun A cave-dweller; a caveman; one who lives in a naturally formed cavity in the rocks, or, by extension, one who has his abode in a dwelling-place of that kind, whether constructed by enlarging a natural cave or by making an entirely new excavation.
• noun Hence, one living in seclusion; one unacquainted with the affairs of the world.
• noun In mammalogy, an anthropoid ape of the genus Troglodytes, as the chimpanzee or the gorilla, especially the former, which was earlier known to naturalists and was called Simia troglodytes.
• noun In ornithology, a wren of the genus Troglodytes or family Troglodytldæ. The term is a misnomer, since no wrens live in caves.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Ethnol.) One of any savage race that dwells in caves, instead of constructing dwellings; a cave dweller, or cave man. Most of the primitive races of man were troglodytes.
• noun (Zoöl.) An anthropoid ape, as the chimpanzee.
• noun (Zoöl.) The wren.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A member of a supposed prehistoric race that lived in caves or holes, a caveman.
• noun by extension Anything that lives underground.
• noun A reclusive, reactionary or out-of-date person, especially if brutish.
• noun The wren, Troglodytes troglodytes.
• noun computing A person who chooses not to keep up-to-date with the latest software and hardware.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun someone who lives in a cave
• noun one who lives in solitude