She sang a beautiful song.
This song is a work by Schubert.
The composer wrote many art songs.
She sang the German art song beautifully.
曲 covers any musical piece, vocal or instrumental, whereas 歌曲 specifically denotes a piece with a sung vocal line.
楽曲 is a broad, formal term for a musical composition of any kind, while 歌曲 narrows this to compositions with lyrics meant to be sung.
歌謡 tends to refer to popular or traditional sung music (like 歌謡曲), while 歌曲 leans toward classical or art-song repertoire.
歌曲 is the general Japanese term for any art song, while リート refers specifically to the German Romantic-era lied.
歌曲 means a sung musical piece, while 戯曲 means a stage play or drama script, despite sharing the character 曲.
song collection; collection of lieder
Compound of 歌 (ka, 'song') and 曲 (kyoku, 'musical piece'). The reading is on'yomi, reflecting its Sino-Japanese origin.