Someone who does not enjoy being outside and would rather spend their time reading comics and playing video games. Not to be confused with nerds, not all geeks are smart. Some can be dumb and or average. Most geeks have a very big knowledge base of fiction.
Geek 1: Oh my god did you hear they're turning Captain America into a Hydra agent?
Geek 2: Yeah *pursues to rant on how Marvel is basically running out of ideas*
I wrote an article discussing how to define geek: www.geekwishlists.com/geekdefinition
When I was growing up I used to geek out over Star Wars.
Describing a person that has an high amount of intelligence with an exception with being annoying or weird.
"I don't like Jeremy, he's a geek"
"He's the teacher's favorite student, since he's a geek"