Definition of "nerd"

nerd

/nɜːd/

noun
plural nerds
1. (slang, sometimes derogatory) A person who is intellectual but generally introverted.
  Quotations
  They particularly enjoy making fun of one of their fellows who is not present, whom they consider a hopeless nerd – until, that is, they learn he is engaged to marry the boss's daughter.
  1953 Advertisement for "Businessman's Lunch", a play by Micheal Quinn, in Patricia Brown, Gloria Mundi
  "We were all geeks and nerds, but he was unusually poorly adjusted," recalls Chess, now a mathematics professor at Hunter College.
  2002, Sam Williams, Free as in Freedom
  "Yes, I am super nerd, and the whole room cracked up," Said Orszag.
  2009 February 28, “Orszag to present budget blueprint”, in WBBH
2. (informal, sometimes derogatory) One who has an intense, obsessive interest in something.
3. (informal, sometimes derogatory) A member of a subculture revolving around intellectualism, technology, video games, fantasy and science fiction, comic books and assorted media.
4. (informal, sometimes derogatory, dated) One who is socially inept or unattractive, but often brainy; a social outcast.