Terms review.
It's time to revisit these definitions, I'm the man to do it, and this is the place to put 'em. -- Joel

nerd (alt nurd) (n.; adj. nerdly) Person rendered socially undesirable largely thru ignorance, typically of fashion, hygiene, proper social behavior, and the importance of appearance. Often but not necessarily associated with unattractive physical attributes. The nerds: One of the Untouchable castes in high school.

geek (n.; adj. geekish) (from “circus geek”, performer of disgusting, self-torturing stunts, prob. from rhyming contrast with "freak") Person with unusually detailed knowledge about one or more obscure, generally uninteresting fields (e.g., "history geek", "computer geek"). Implication is that such extreme interest in knowledge is suspect and that pursuing the expertise excludes a normal social life. A geek is often also a nerd.

freak (n.; adj. freakish, freaky) (from “freak of nature”, deformed creature, via “circus freak”, a living or preserved specimen of physical abnormality) Person socially unfit due to some behavioral attribute over which they have no control, such as inappropriate outbursts (the "freak out") or permanent confusion. Use for actual disabilities is considered excessively cruel. Since their condition is involuntary, freaks are less reviled than nerds. The freaks: High school students considered mentally unable to participate in the social structure, usually due to habitual drug use.