The Collaborative International Dictionary of English v.0.48:

Siva \Si"va\, n. [Skr. Civa, properly, kind, gracious.] (Hindoo
   Myth.)
   One of the triad of Hindoo gods. He is the avenger or
   destroyer, and in modern worship symbolizes the reproductive
   power of nature.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Siva
    n 1: the destroyer; one of the three major divinities in the
         later Hindu pantheon [syn: Siva, Shiva]