Ugly, socially inept, boring male (usually, but some of them can be female) whom nobody wants to fuck. Some of them grow up to be another abomination: yuppies. Many of them have a mild form of schizophrenia and have very limited breadth of thought process and cultural exposure. A lot of geeks are latent gays, though they try to mask it, but the reality is that they suck in bed whether with homo- or heterosexual partner. The geekness has a potential cure: gym time and outdoors. Geeks usually need to get a life.
Contrary to popular belief, someone being a software engineer or similar high-level computer professional does not equal "geek"--especially if they have education in the field. A well-balanced person who is athletic, well-traveled, true art lover, morally sound and in general has a life can be a computer professional and not be a geek.
I need to take a shower asap, I've been sitting near a geek... who knows it might be infectious.