A geek is any person who is specially intelligent or talented in any specific area of expertise. Geeks are not to be confused with nerds who are simply dorky, uncoordinated and usually lack social skills.
Geeks often have some sort of social skills yet are dorky (though there are many geeks who are not also dorks).
Kathleen is the biggest choir geek in school.
Bob knows all about computer programming
he's the company computer geek.