Source : Webster's Revised Unabridged Dictionary (1913)

Vaishnava \Vaish"na*va\ (v[imac]sh"n[.a]*v[.a]), n. [Skr.
   vaish[.n]ava.] (Hindu Myth.)
   A worshiper of the god Vishnu in any of his incarnations.

Source : WordNet®

Vaishnava
     n : worshipper of Vishnu