@EricLNZ technically, you are correct. But I think the word "song" has generally been accepted as most musical pieces. But to be correct it is "instrumental music".
Many instrumental and orchestral works are composed or titled as "Songs" or "Dances" without actually having lyrics or choreography. The titles are meant to have an evocative effect on the listener, not necessarily to be taken literally.
Many of Debussy's orchestral works are classified as "songs" but come without lyrics, and Mozart did not include choreography for his minuets, which are classified as "dances."