The Collaborative International Dictionary of English v.0.48:

Redskin \Red"skin`\ (-sk?n`), n.
   1. A common appellation for a North American Indian; -- so
      called from the color of the skin. It is now considered
      pejorative by some persons of North American Indian
      heritage. --Cooper.
      [1913 Webster +PJC]

   2. (Football) A member of the Washington Redskins, a football
      team.
      [PJC]

WordNet (r) 3.0 (2006):

Redskin
    n 1: (slang) offensive term for Native Americans [syn:
         Redskin, Injun, red man]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "redskin":
   American Indian, Amerind, Australian aborigine, Bushman, Caucasian,
   Indian, Malayan, Mister Charley, Mongolian, Negrillo, Negrito,
   Negro, Oriental, Red Indian, WASP, black, black man, blackfellow,
   boy, brown man, burrhead, colored person, coon, darky, gook, honky,
   jigaboo, jungle bunny, nigger, niggra, ofay, paleface, pygmy,
   red man, slant-eye, spade, the Man, white, white man, whitey,
   yellow man



The Devil's Dictionary (1881-1906):

RED-SKIN, n.  A North American Indian, whose skin is not red -- at
least not on the outside.