A word for voices, and for cheap bargains
In ordinary English a song is a piece of music meant to be sung: verses, a tune, a performance by one voice or several. The same noun covers the act of singing itself, a bird’s territorial music, a whale’s long-distance call, and, more loosely, any short recorded track people stream or whistle. In older literary English it could also mean verse as such, the kind of poem once meant to travel with a lyre. A separate, well-worn idiom treats a song as something nearly worthless. To buy a thing for a song is to get it for next to nothing.
None of this is a late fashion imported with court music. English did not take the noun from French chanson or from Latin cantus. It inherited the word from its own Germanic stock, then stretched the senses as the language changed.
From Old English into the modern spelling
The immediate ancestor is Old English sang, also written song. In that period the noun already named the voice, vocal music, the skill of singing, and a metrical piece made to be sung, including psalms and other poems. It was native inheritance, present in English before the Norman Conquest, not a loan from the Romance vocabulary of churches and courts.
Middle English kept both spellings, sang and song, and a thicket of related uses: lyrics, hymns, ballads, narrative verse, even charms and oft-repeated sayings. The form with o won out in the standard language. That vowel is not an accident of later fashion. Before a nasal plus a velar, Old English a often rounded, which is why lang, strang, and sang sit beside modern long, strong, and song. Scots still uses sang for the same noun, a reminder that the older vowel did not vanish everywhere in Britain.
The same root as sing
Song is the noun counterpart of the verb sing. They are not two separate coinages glued together later. In Indo-European and Germanic morphology, related words often differ by vowel grade rather than by an added suffix. The verb reflects an e-grade of the root; the noun reflects an o-grade of the same root. English still shows the pattern in the strong verb’s principal parts: sing, sang, sung. The noun song belongs with that o-grade, the same vocalic family as the past tense sang.
Behind Old English stands Proto-West Germanic sangu and, further back, Proto-Germanic sangwaz, reconstructed as a masculine noun meaning singing or a song. That Germanic form is usually taken as an o-grade nominal built on the verb singwaną, from a Proto-Indo-European root whose core sense was to sing or to recite in a chanted voice. The starred forms are comparative reconstructions, not attested spellings on clay or parchment, but the Germanic descendants line up closely enough to make the family tree reasonably secure.
Cognates are easy to hear across the North Sea and the Baltic. Old Norse had a matching noun; modern Icelandic has söngur; Norwegian still uses both song and sang depending on the written standard; Swedish has sång; Dutch has zang; German keeps Sang beside the more everyday Gesang; Gothic, the earliest well-attested Germanic language, has saggws. English later sent its own form back out as a loan: Dutch and German both use Song, with a capital S in German, for a popular or recorded number as opposed to the older native nouns.
A Germanic word in a Latin-shaped Europe
What the family does not supply is a crowd of obvious cousins outside Germanic. The usual Indo-European verb for singing is the one behind Latin canere, the source of English chant, canticle, and, through French, a large part of the vocabulary of church music. Many other languages built their verbs for singing from roots that meant to cry or shout. Irish gaibim is literally to take, and only later to take up a melody.
Some handbooks link the Germanic root, cautiously, to Ancient Greek omphē, a voice, especially a divine one, and to Welsh dehongli, to explain or interpret. Those connections are disputed. They are worth mentioning because they show how thin the non-Germanic evidence is, not because they settle the question. If the Greek and Welsh words do belong, they still sit at a distance: a god’s oracle-voice, an act of interpretation, not a folk tune.
Senses that grew, and a few that faded
By late Old English the noun could already name a bird’s musical call. That use never left. Naturalists later sharpened it. In ornithology a song is the structured vocalization, often from a male, used to hold territory or attract a mate, as against a shorter call.
Literary English stretched the word toward poetry that aims at feeling rather than at plot. Middle English also used it for liturgical pieces, narrative verse, and, in some contexts, an incantation. One biblical sense, now obsolete as everyday English, treated a person as a song in the meaning of a laughing-stock, someone turned into the subject of other people’s verses of mockery.
The bargain idiom is later and more worldly. By the early seventeenth century, in Shakespeare’s All’s Well That Ends Well, selling a manor for a song already meant selling it for a pittance. Old French had a matching image with son, meaning sound, which suggests the joke was available in more than one language: music as something you can have for almost no money. Song and dance as a stage pairing is a nineteenth-century theatrical label; by the 1890s it had become a dismissive name for a long, insincere explanation.
A minor Middle English adjective, songly, meaning worthy of song, did not survive. The verb, meanwhile, picked up slang of its own, including the underworld sense of confessing to the authorities, but that belongs to sing, not to the noun.
What the spelling still records
The origin of the word song sits in the same Germanic ablaut set as sing and sang. The modern spelling with o is the same nasal rounding that gave English long and strong, while Scots sang preserves the older vowel. That is the history still audible in the word: not a borrowed chanson, but a native noun that grew beside its verb.