Wordnet 3.0
NOUN (1)
1. 
 someone who has exceptional intellectual ability and originality; 
- Example: "Mozart was a child genius"- Example: "he's smart but he's no Einstein"[syn: genius, mastermind, brain, brainiac, Einstein]
WordNet (r) 3.0 (2006):
brainiac
    n 1: someone who has exceptional intellectual ability and
         originality; "Mozart was a child genius"; "he's smart but
         he's no Einstein" [syn: genius, mastermind, brain,
         brainiac, Einstein]