geek

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A person regarded as foolish, inept, or clumsy.
2. n. A person who is single-minded or accomplished in scientific or technical pursuits but is felt to be socially inept.
3. n. A carnival performer whose show consists of bizarre acts, such as biting the head off a live chicken.
4. v. To excite emotionally: I'm geeked about that new video game.

Wiktionary

1. n. A carnival performer specializing in bizarre and unappetizing behavior.
2. n. A person who is intensely interested in a particular field or hobby and usually antisocial. Often used with an attributive noun.
3. n. An expert in a technical field, particularly one having to do with computers.
4. n. The subculture of geeks; an esoteric subject of interest that is marginal to the social mainstream; the philosophy, events, and physical artifacts of geeks.
5. n. An unfashionable or socially undesirable person.
6. n. A look.
7. v. To get high on cocaine.

GNU Webster's 1913

1. n. A performer in a carnival, often presented as a wild man, who performs grotesquely disgusting acts, such as biting the head off a live chicken or snake.
2. n. Any eccentric or strange person; an oddball; an eccentric.
3. n. A student who is socially inept and a misfit in his class, especially one who is an intellectual; a nerd; a dork.
4. n. An intellectually inclined person, especially one who is interested in scientific or technical subjects; ; -- originally a deprecatory and contemptuous term, but in the 1990's, with the increase in popularity of computers and the frequency of accumulation of great wealth by computer entrepreneurs, it has come to be used with noticeable frequency by technically competent people to refer to themselves, ironically and sometimes proudly.

WordNet 3.0

1. n. a carnival performer who does disgusting acts
2. n. a person with an unusual or odd personality