What is "horologion"

n. A liturgical book in the Eastern Church, containing the daily offices corresponding to the Western breviary.

The Horologion (; Church Slavonic: Часocлoвъ, Chasoslov, ) or Book of hours provides the fixed portions (Greek: , akolouthiai) of the Divine Service or the daily cycle of services as used by the Eastern Orthodox and Eastern Catholic churches. Into this fixed framework, numerous moveable parts of the services are inserted.

In its original sense, a horologion (Greek: ὠρολόγιον, "the hour-teller" from ὥρα hṓra "hour" and -λόγιον -logion, "teller") or Latin horologium was any device or structure for keeping time, such as a sundial or the Tower of the Winds in Athens.

Horologion fallax is a species of beetle in the family Carabidae, the only species in the genus Horologion.