[ gdw]
The adjectival use of nocturne, meaning ‘of the night’ (see DMF and DMLBS) does not seem to be attested in A-N, and only its use as a substantive in a liturgical context is found.
The synonyms nocturne, nocturnel, nuital and nuiturnel all represent different stages of the development of Latin nocturnus and nocturnalis into French.
Nobel’s alternative interpretation of the word in Anc Test as referring to the office of matins itself (see Anc Test ii 326-27 and 537) appears unnecessary.