The Collaborative International Dictionary
Menologium \Men`o*lo"gi*um\, Menology \Me*nol"o*gy\, n.; pl. L. Menologia, E. Menologies. [NL. menologium, fr. Gr. mh`n month + lo`gos discourse : cf. F. m['e]nologe.]
A register of months.
--Bp. Stillingfleet.(Gr. Church) A brief calendar of the lives of the saints for each day in the year, or a simple remembrance of those whose lives are not written.
Wikipedia
Menologium (from the Greek μηνολόγιον menológion, from μήν mén "a month"; Latin menologium), also written menology, and menologe, is a service-book used in the Eastern Orthodox Church and those Eastern Catholic Churches which follow the Rite of Constantinople.
From its derivation, 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.