noun
A musical composition inspired by or evocative of the night, often for piano. Used in classical music contexts.
ショパンのノクターンはとても美しい。
Chopin's nocturnes are very beautiful.
夜想曲 is the Japanese translation of 'nocturne', but ノクターン is more common in everyday music talk.
Borrowed from French 'nocturne', ultimately from Latin 'nocturnus' (of the night).