'Song' is PIE *sengwh- (to make an incantation) — the oldest concept of song was bound up with ritual.
A short musical composition for the human voice, typically with words; more broadly, any musical sounds produced by a bird, whale, or other animal.
From Old English 'sang' or 'song' (a song, a poem, a chant, music), from Proto-Germanic *sangwaz (a song, a singing), derived from the PIE root *sengʷʰ- (to sing, to make a melodic sound, to chant, to intone an incantation). The word is the nominal form of the verb 'sing' — a 'song' is literally 'that which is sung,' the substantive product of the act of singing. The PIE root *sengʷʰ- suggests that the earliest concept
The phrase 'swan song' — meaning a final performance before death — comes from the ancient Greek belief that mute swans, silent throughout their lives, sing one beautiful song just before dying. The belief is false (swans do not do this), but the metaphor has been irresistible for over two millennia.