A system of forty alphabetic signs invented presumably by Cyril about a.d. 863 for writing Slavonic. Though reminiscent of some other alphabets, it is largely original. It was supplanted probably in the tenth century by the Cyrillic alphabet, the basis of modern alphabets for Russian, Bulgarian, Ukrainian, etc. Several important manuscripts survive written in these characters, two gospel manuscripts (Zographensis, Marianus), a lectionary (Assemanianus), psalter (Sinaiticum), prayer-book (Euchologium Sinaiticum), and fragments of homilies (Clozianus).