The Collaborative International Dictionary of English v.0.48:

Kava \Ka"va\, n. [Polynesian.] (Bot.)
   A species of Macropiper (Macropiper methysticum), the
   long pepper, from the root of which an intoxicating beverage
   is made by the Polynesians, by a process of mastication;
   also, the beverage itself. [Written also kawa, kava, and
   ava.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

kava
    n 1: an alcoholic drink made from the aromatic roots of the kava
         shrub [syn: kava, kavakava]