menaion

from The Century Dictionary.

• noun In the Gr. Ch., any one of the twelve volumes, each volume answering to one month, which together contain a methodical digest of all the offices to be read in commemoration of the church saints. A full set of the menaia constitutes the complete Greek breviary.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Eccl.) A work of twelve volumes, each containing the offices in the Greek Church for a month; also, each volume of the same.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The annual fixed liturgical cycle of services used in the Eastern Orthodox and Greek-Catholic Churches, containing a list of the services and large collection of liturgical texts for an entire month. Twelve volumes are usually offered for the year, as a set known as the menaia.