Menologion (from the Greek menológion, from mén "a month"; Latin Menologium), also written Menology and Menologe, a service-book used in the Eastern Orthodox Church and those Eastern Catholic Churches which follow the Rite of Constantinople. From its derivation the term Menologium means "month-set", in other words, a book arranged according to the months. Like a good many other liturgical terms (e.g. lectionary), the word has been used in several quite distinct senses.