late 15c., ultimately from Arabic bazahr, from Pers. pad-zahr "counter-poison," from pad "protecting, guardian, master" (from Iranian *patar-, cf. Avestan patar-, from PIE *pa-tor-, from base *pa- "to protect, feed") + zahr "poison" (from O.Ir. *jathra, from PIE *gwhn-tro-, from base *gwhen- "to strike, kill"). Originally "antidote," later specifically in reference to a concoction from solid matter found in the stomachs and intestines of ruminants, which was held to have antidotal qualities (1570s).