Irmos

The irmos is the initial verse of each individual ode

Ode

Ode is a lyrical verse. A classic ode is structured in three major parts: the strophe, the antistrophe, and the epode...

 in a canon

Canon (hymnography)

A canon is a structured hymn used in a number of Eastern Orthodox services. It consists of nine odes, sometimes called canticles or songs depending on the translation, based on the Biblical canticles. Most of these are found in the Old Testament, but the final ode is taken from the Magnificat and...

, sung by the choir; from the Greek verb "to tie," meaning that it poetically connects the ode to the subject of the canon.

The irmos is the initial verse of each individual ode

Ode

Ode is a lyrical verse. A classic ode is structured in three major parts: the strophe, the antistrophe, and the epode...

 in a canon

Canon (hymnography)

A canon is a structured hymn used in a number of Eastern Orthodox services. It consists of nine odes, sometimes called canticles or songs depending on the translation, based on the Biblical canticles. Most of these are found in the Old Testament, but the final ode is taken from the Magnificat and...

, sung by the choir; from the Greek verb "to tie," meaning that it poetically connects the ode to the subject of the canon.

The irmos presents a pattern for all of the troparia which follow within a given ode. It also gives its name to the irmologic forms of Byzantine chant.