Irmologion
![Irmologion, (Melchite Use). Depicted are Irmos 705-709 (Syriac Sertâ book script. 11th century, Saint Catherine's Monastery, Mount Sinai. Now part of the Schoyen Collection, MS 577.](/Images/godic/202501/21/Syriac_Sertâ_book_script1642.jpg")
Irmologion (Greek: εἱρμολόγιον heirmologion) is a liturgical book of the Eastern Orthodox Church and those Eastern Catholic Churches which follow the Byzantine Rite. It contains irmoi for the various canons which are chanted during the morning service. The book Irmologion derives from εἱρμός heirmos meaning "link". The irmos is a melodic model which preceded the composition of the odes. Hence, λογεύω logeuō means "to collect", because within the irmologic repertoire there are more canons (or akrosticha) than irmoi.