I use the term Geek a lot but I use it in two different contexts with no differentiation in spelling, notation, or pronunciation. Kind of like the F word. It's all about context. You can look up the word in a dictionary but here are the two definitions I use.
Definition of GEEK
1. Having an affinity for video games, comic books, science fiction and fantasy (in any medium), TV and movies, technology, and related things. So that covers a lot of ground but it's still a very distinct set of subjects that you know when you see it. What is and is not Geek is arbitrary and there is no designated authority making the decision but some things are just accepted (ie Star Wars, Star Trek, Marvel and DC Comics, etc.)
2. The Wil Wheaton and Simon Pegg school of thought:
"You find the things that you love, and you love them the most that you can."~ Wil Wheaton (Recommended viewing: Wil Wheaton - Why it's awesome to be a nerd)
“Being a geek is all about being honest about what you enjoy and not being afraid to demonstrate that affection. It means never having to play it cool about how much you like something.” ~ Simon Pegg
In other words, it's about being passionate and proud about something, anything. So you can be a computer geek or a music geek or a fashion geek or a film geek or a...