[EricH]

Dictionary definition has very little to do with connotation.
Dictionary definition has even less to do with context.
Connotation is not defined by nerds, but by everybody.
Non-nerds will have a different-ish definition of the word "nerd"--defined by connotation.

Incidentally, if I were to call synth3tk a particular term, I'd expect him to be pretty mad at me. If he were to call me that same term, I'd probably figure it as a compliment, or him calling me a friend. (Term not stated for various reasons--including me not wanting to have him mad at me.) One word, two different connotations, both depending on context and who's actually saying it.

So, if a nerd-type (there are many) calls someone a nerd, it can be seen as a compliment. If a jock-type calls someone a nerd, it's probably an insult. If a jock-type calls someone a jock, it's probably a compliment. But if a nerd-type calls someone a jock, it's probably not complimentary.

Context and connotation are key to determining whether a word is good or bad. "Nerd" has a negative connotation--unless someone who is a nerd-type calls you one. Same for "jock". Clear?