In Hinduism, Vrtra (Sanskrit, “storm cloud”) is a dark cloud of ignorance and sloth personified by a demon serpent that was vanquished by Indra. The story is the subject of several Vedic hymns, mentioned in the Rg Veda. A.G.H.
Jordan, Michael, Encyclopedia of Gods, New York, Facts On File, Inc. 1993, p. 289
Bowker, John, The Oxford Dictionary of World Religions, New York, Oxford University Press, 1997, p. 1030