The Collaborative International Dictionary of English v.0.48:

American Indian \American Indian\ n.
   1. a red-skinned member of a race of people living in North
      America when Europeans arrived.

   Syn: Indian, native American, Amerindian, Red Indian
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

American Indian
    n 1: a member of the race of people living in America when
         Europeans arrived [syn: Indian, American Indian, Red
         Indian]
    2: any of the languages spoken by Amerindians [syn: Amerind,
       Amerindian language, American-Indian language, American
       Indian, Indian]