The Collaborative International Dictionary of English v.0.48:

Koumiss \Kou"miss\, n. [Russ. kumys; of Mongolian origin.]
   An intoxicating fermented or distilled liquor originally made
   by the Tartars of central Asia from mare's or camel's milk.
   It can be obtained from any kind of milk, and is now largely
   made in Europe. [Written also koumyss, kumiss, kumis,
   kumish, and kumys.]
   [1913 Webster]

         Koumiss has from time immemorial served the Tartar
         instead of wine or spirits.              --J. H.
                                                  Newman.
   [1913 Webster]

WordNet (r) 3.0 (2006):

koumiss
    n 1: an alcoholic beverage made from fermented mare's milk; made
         originally by nomads of central Asia [syn: koumiss,
         kumis]