1. A non-classical avatāra of the Hindu god Viṣṇu. He is worshipped in traditions influenced by the Pañcarātra (e.g. among the Śrī-Vaiṣṇavas). Envisaged as primordial teacher, he has absorbed features of the Buddha.
2. A demon of Hindu mythology who stole the Vedas and was killed by Viṣṇu.
"Hayagrīva." The Concise Oxford Dictionary of World Religions. . Encyclopedia.com. (September 24, 2018). http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/hayagriva
"Hayagrīva." The Concise Oxford Dictionary of World Religions. . Retrieved September 24, 2018 from Encyclopedia.com: http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/hayagriva