Ŭn'der-sŏng, n.
n. 1. The burden of a song; the chorus.
Menalcas shall sustain his under-song. Dryden.
Sense 2. Subordinate and accompanying meaning; accompaniment; under-tone.
In the very best [poetry] there is often an under-song of sense which none but the poetic mind . . . can comprehend. Landor.