Airyana-ishejô (Zend). The name of a prayer to the “holy Airyamen”, the divine aspect of Ahriman before the latter became a dark opposing power, a Satan. For Ahriman is of the same essence with Ahura Mazda, just as Typhon-Seth is of the same essence with Osiris (q.v.).
Source: H.P.Blavatsky - The Theosophical Glossary