The Collaborative International Dictionary of English v.0.48:

haoma \haoma\ n.
   A leafless East Indian vine (Sarcostemma acidum); its sour
   milky juice was formerly used to make an intoxicating drink.

   Syn: soma, Sarcostemma acidum.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Sarcostemma acidum
    n 1: leafless East Indian vine; its sour milky juice formerly
         used to make an intoxicating drink [syn: soma, haoma,
         Sarcostemma acidum]