The Collaborative International Dictionary of English v.0.48:

Half-breed \Half"-breed`\ (-br[=e]d`), a.
   Half-blooded.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Half-breed \Half"-breed`\, n.
   A person who is half-blooded; the offspring of parents of
   different races, especially of the American Indian and the
   white race.
   [1913 Webster]

WordNet (r) 3.0 (2006):

half-breed
    adj 1: (of animals) having only one purebred parent [syn: half-
           blooded, half-bred, half-breed]
    n 1: an offensive term for an offspring of parents of different
         races (especially of Caucasian and American Indian
         ancestry)