Nocturn

Noun

noc=turn

CIDE DICTIONARY

Nocturn, n. [F. nocturne, fr. L. nocturnus. See Nocturnal, and cf. Nocturne.].

An office of devotion, or act of religious service, by night. [1913 Webster]
One of the portions into which the Psalter was divided, each consisting of nine psalms, designed to be used at a night service. Hook. [1913 Webster]

Nocturn, n. RC Ch. a part of matins orig. said at night.

Etymology

ME f. OF nocturne or eccl.L nocturnum neut. of L nocturnus: see NOCTURNAL

For further exploring for "Nocturn" in Webster Dictionary Online