nerd

Short definition from Wiktionary

Noun

1. 1
   A person who is intellectual but generally introverted.
2. 2
   One who has an intense, obsessive interest in something.
3. 3
   A member of a subculture revolving around intellectualism, technology, video games, fantasy and science fiction, comic books and assorted media.
4. 4
   One who is stupid and socially inept or unattractive; a social outcast.
5. 5
   Initialism of nonerosive reflux disease.

Proper noun

1. 1
   Alternative form of NERDS.