bright star in the tail of the constellation Cygnus the Swan, by 1741, from Arabic Al Dhanab al Dajajah "the Hen's Tail."
"a young swan," c. 1400, also signet before 17c., from Anglo-French cignet (mid-14c.), Anglo-Latin cygnettus, diminutives of Old French cigne, cisne "swan" (12c., Modern French cygne), from Latin cygnus, from Greek kyknos, which has been the subject of "abundant discussion" (Beekes) and is perhaps from PIE *(s)keuk- "to be white" (compare Sanskrit socati "to lighten, glow," sukra- "light, clear, white"). Spanish, Portuguese cisne, Italian cecero are from Medieval Latin cecinus, cicinus, a corruption of the classical Latin word.
"a song, a short, simple poem intended to be sung," c. 1600, from French chanson, from Old French chançon "song, epic poem" (12c.), from Latin cantionem (nominative cantio) "song," from past participle stem of canere "to sing" (from PIE root *kan- "to sing").
c. 1300, melodie, "vocal or instrumental music, a succession of agreeable musical sounds," from Old French melodie "music, song, tune" (12c.) and directly from Late Latin melodia "a pleasant song" (in Medieval Latin also "music" generally), from Greek melōidia "a singing, a chanting; a choral song, a tune for lyric poetry," from melos "song, part of song; limb, member" (a word of uncertain origin) + ōidē "song, ode" (see ode). From late 14c. as "a song of clear and balanced form." Sense of "a series of tones so related to one another as to produce a distinct musical phrase or idea, a tune" is by c. 1600. Meaning "the principal voice-part in a harmonic composition" is by 1880.
Muse of tragedy, originally of song and musical harmony, from Latin, from Greek Melpomene, literally "songstress," from melpein "to sing, to celebrate with song and dance," a word of unknown origin.