"the fabled song of a dying swan," 1831, from swan (n.) + song (n.); a translation of German Schwanengesang. The singing of swans before death was alluded to by Chaucer (late 14c.). Hence, figuratively, "last work before a writer or composer's death" (by 1837).

large, web-footed swimming bird, stately and graceful in the water, noted for its long neck and white down; Old English swan "swan," from Proto-Germanic *swanaz "singer" (source also of Old Saxon swan, Old Norse svanr, Danish svane, Swedish svan, Middle Dutch swane, Dutch zwaan, Old High German swan, German Schwan), probably etymologically "the singing bird" (from PIE root *swen- "to make sound"). If so, it is related to Old English geswin "melody, song" and swinsian "to make melody."

In classical mythology the bird was sacred to Apollo and to Venus. The ancient Indo-European supernatural swan-maiden was so called by mythographers from 1829 (from German). Swan dive is recorded from 1898. Swanherd "one who tends swans" is late 15c. Swannage (late 14c.) was a payment for the right to keep swans.

"musical or rhythmic vocal utterance," Old English sang "voice, vocal music, song, art of singing; metrical composition adapted for singing, psalm, poem," from Proto-Germanic *songwho- (source also of Old Norse söngr, Norwegian song, Swedish sång, Old Saxon, Danish, Old Frisian, Old High German, German sang, Middle Dutch sanc, Dutch zang, Gothic saggws), from PIE *songwh-o- "singing, song," from *sengwh- "to sing, make an incantation" (see sing (v.)).

Of the musical call of some birds from late Old English. In literature often loosely, "poem focusing on arousal of emotions" of the sort traditionally sung to the lyre. Middle English had songly "worthy of song" (mid-14c.).

The colloquial phrase for a song "for a trifle, for little or nothing" is from "All's Well" III.ii.9 (the identical image, por du son, is in Old French). With a song in (one's) heart "feeling joy" is attested by 1859. Song and dance as a form of stage act is attested from 1872; the figurative sense of "rigmarole" is by 1895.

proverbial for "something extremely rare or non-existent," late 14c., from Juvenal ["Sat." vi. 164], cygnus niger, but the real thing turned up later in Australia (Chenopsis atratus).

"Do you say no worthy wife is to be found among all these crowds?" Well, let her be handsome, charming, rich and fertile; let her have ancient ancestors ranged about her halls; let her be more chaste than all the dishevelled Sabine maidens who stopped the war—a prodigy as rare upon the earth as a black swan! yet who could endure a wife that possessed all perfections? I would rather have a Venusian wench for my wife than you, O Cornelia, mother of the Gracchi, if, with all your virtues, you bring me a haughty brow, and reckon up Triumphs as part of your marriage portion. [Juvenal]

White crow was a similar figure in English. Blue dahlia also was used 19c. for "something rare and unheard of." In ancient Greece, leukos korax "white raven" was "an unheard-of thing"

mid-15c., "music sung from written notes" instead of from memory or by ear, from song (n.) + prick (n.) in a Middle English sense of "mark indicating pitch" in music; from the Old English sense of prick as "dot or small mark made in writing." Compare counterpoint (n.2)).

Nares' "Glossary" defines prick-song as "Music written down, sometimes more particularly music in parts .... When opposed to plain-song, it meant counter-point, as distinguished from mere melody."

The "Collection of Ancient English Airs" [ed. W. Chappell, 1840] defines it as "Harmony written or pricked down in opposition to plain-song, where the descant rested with the will of the singer." Among the old poets, prick-song was used of the nightingale's song, it being full of rich beauty and regular music. They also speak of the cuckoo's plain-song.

in reference to parts or objects resembling the curved neck of a swan, by 1680s, from swan (n.) + neck (n.).

also plainsong, unisonous vocal music used in the Christian churches in the earliest centuries, mid-15c., translating Latin cantus planus, French plain chant; see plain (adj.) + song (n.).

also songbird, "bird that sings," 1704, from song (n.) + bird (n.1).

also songbook, Old English sangboc "church service book, breviary;" see song (n.) + book (n.). The meaning "collection of songs bound in a book" is from late 15c.

also singsong, of music, prayers, etc., "monotonously repetitive and unvarying," 1734, from earlier use as a noun meaning "a jingling ballad" (c. 1600), from sing (v.) + song (n.).