The Collaborative International Dictionary of English v.0.48:

Brahman \Brah"man\, Brahmin \Brah"min\, n.; pl. Brahmans,
   Brahmins. [Skr. Br[=a]hmana (cf. Brahman worship, holiness;
   the God Brahma, also Brahman): cf. F. Brahmane, Brachmane,
   Bramine, L. Brachmanae, -manes, -mani, pl., Gr. ?, pl.]
   1. A person of the highest or sacerdotal caste among the
      Hindus.
      [1913 Webster]

   Brahman bull (Zool.), the male of a variety of the zebu, or
      Indian ox, considered sacred by the Hindus.
      [1913 Webster]

   2. a person from an old, respected, and usually wealthy
      family who has considerable social or political influence;
      -- a term used especially in New England; as, a Boston
      brahmin.
      [PJC]

WordNet (r) 3.0 (2006):

brahmin
    n 1: a member of a social and cultural elite (especially a
         descendant of an old New England family); "a Boston
         brahman" [syn: brahman, brahmin]
    2: a member of the highest of the four Hindu varnas; "originally
       all brahmans were priests" [syn: brahman, brahmin]
    3: the highest of the four varnas: the priestly or sacerdotal
       category [syn: brahman, brahmin]
    4: any of several breeds of Indian cattle; especially a large
       American heat and tick resistant greyish humped breed evolved
       in the Gulf States by interbreeding Indian cattle and now
       used chiefly for crossbreeding [syn: Brahman, Brahma,
       Brahmin, Bos indicus]