Wiktionary
n. (plural of nocturn English)
Wikipedia
Nocturns ( Latin: Nocturni or Nocturna) are divisions of Matins, the night office of the Christian Liturgy of the Hours. A nocturn consists of psalms with antiphons followed by three lessons, which are taken either from scripture or from the writings of the Church Fathers. The office of Matins is composed of one to three nocturns. The term nocturn has been used since Late Antiquity. In 1970, following the Second Vatican Council, a revision of the Roman Breviary discontinued the use of nocturns when the office of Matins was reformed as the Office of Readings.
Usage examples of "nocturns".
From the depths of sleep he heard the three nocturns of the new day's Matins in the adjacent sanctuary.
He has coaxed a few out of their hiding places when, late at night before Nocturns, he can't sleep and wanders like a shade from one place to another within the compound, rootless and lost.