The opening hymn of each ode of a canon. In the original Greek text, all the remaining troparia in the ode follow the same meter as the irmos.
In the canon sung in Matins an irmos is a stanza setting the pattern for those following it. 'Eirmos' = 'series'.
(pl. Heirmoi, Irmosi) a hymn that stands as the first troparion in each ode of a kanon and serves as a thematic link between the Scriptural canticles and the feast being celebrated. In the Greek originals, the h. established the melodic and metric model used in subsequent stanzas of each ode.
the opening stanza of each canticle of a Canon.
This is the Theme Song of each Ode of the Canon. The word Irmos means link, since originally the Troparia that followed it were sung in the same rhythm, and thus were linked to it.
The irmos is the initial verse of each individual ode in a canon, sung by the choir; from the Greek verb "to tie," meaning that it poetically connects the ode to the subject of the canon.