1715, "Parsee sacred book" (in full, Zend-Avesta, 1620s), from Old Persian zend, from Pahlavi zand "commentary," from Avestan zainti- "knowledge," from PIE root *gno- "to know." First used 1771 in reference to the language of the Zend-Avesta by French scholar Abraham Hyacinthe Anquetil-Duperron (1731-1805).