This term or one of its cognates (vetulyaka, vetullaka, vaipulyavada, etc.) is found in a few Theravada sources, e.g. at Kathavatthu XXIII. Originally, the terms designated a pre- (possibly proto-) Mahayana doctrine that was regarded as heretical by the more orthodox. Later, some Theravada writers may have adopted it as a polemical label for Mahaya...