The term "Crypto-Buddhism" (Prachanna Bauddha) was used by some opponents of Advaita Vedanta to suggest that Shankara's philosophy, while ostensibly Vedic, borrowed heavily from Mahayana Buddhist concepts, particularly Shunyata (emptiness) and Vijnanavada (consciousness-only). Critics argued that Advaita's concept of an impersonal Brahman and the illusory nature of the world resembled Buddhist ideas.