A sticheron (Greek: στιχηρόν "set in verses"; plural: stichera; Greek: στιχηρά) is a hymn of a particular genre that has to be sung during the morning (Orthros) and evening service (Hesperinos) of the Orthodox Church and those Eastern Catholic Churches which follow the Byzantine Rite.
Stichera are usually sung in alternation with or immediately after psalm or other scriptural verses. These verses are known as stichoi (sing: stichos), but sticheraric poetry usually follows the hexameter and is collected in an own book called sticherarion (Greek: στιχηράριον). A sticherarion is a book containing the stichera for the morning and evening services throughout the year, but chant compositions in the sticheraric melos can also found in other liturgical books like the Octoechos or the Anastasimatarion, or in the Anthology for the Divine Liturgy.
In the current traditions of Orthodox Chant, the sticherarion as a hymn book was also used to call a chant genre sticheraric melos, which is defined by its tempo and its melodic formulas according to the eight modes of the Octoechos. Although the hymns of the sticherarion have to be sung in the same melos, there is no direct relation with the poetic hymn genre, because its musical definition rather follows the practice of psalmody. Today the sticheraric melos as opposed to the troparic melos are two different cycles of the Octoechos.
In the past they had been closer related by the practice of psalmody, and a troparion which is nothing else than a refrain sung with psalmody, might become a more elaborated chant from a musical point of view, so that it is sung thrice without the psalm verses, but with the small doxology. The troparion in its melodic form tends to move towards the sticheraric or even papadic melos, and this way, it becomes an own chant genre by itself.