Osiris \O*si"ris\, prop. n. [L., fr. Gr. ?; of Egyptian origin.] (Myth.) One of the principal divinities of Egypt, the brother and husband of Isis. He was figured as a mummy wearing the royal cap of Upper Egypt, and was symbolized by the sacred bull, called Apis. Cf. {Serapis}. -- {O*sir"i*an}, a. [1913 Webster]