The Collaborative International Dictionary of English v.0.48:

Aryan \Ar"yan\ ([aum]r"yan or [a^]r"[i^]*an), n. [Skr. [=a]rya
   excellent, honorable; akin to the name of the country Iran,
   and perh. to Erin, Ireland, and the early name of this
   people, at least in Asia.]
   1. One of a primitive people supposed to have lived in
      prehistoric times, in Central Asia, east of the Caspian
      Sea, and north of the Hindu Kush and Paropamisan
      Mountains, and to have been the stock from which sprang
      the Hindu, Persian, Greek, Latin, Celtic, Teutonic,
      Slavonic, and other races; one of that ethnological
      division of mankind called also Indo-European or
      Indo-Germanic.
      [1913 Webster]

   2. The language of the original Aryans. [Written also
      Arian.]
      [1913 Webster]

   3. (Nazism) a non-Jewish caucasian of Nordic stock; -- a
      classification used by Nazis, having no anthropological
      basis. [Written also Arian.]
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Aryan \Ar"yan\ ([aum]r"yan or [a^]r"[i^]*an), a.
   Of or pertaining to the people called Aryans; Indo-European;
   Indo-Germanic; as, the Aryan stock, the Aryan languages.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Aryan
    adj 1: of or relating to the former Indo-European people; "Indo-
           European migrations" [syn: Indo-European, Indo-Aryan,
           Aryan]
    n 1: (according to Nazi doctrine) a Caucasian person of Nordic
         descent (and not a Jew)
    2: a member of the prehistoric people who spoke Proto-Indo
       European [syn: Aryan, Indo-European]