undersong

1. (figuratively) Subordinate and underlying idea, meaning or atmosphere; undertone.Examples: "Defective however and faulty must be the composition in prose, which you and I with all our study and attention cannot understand. In poetry it is not exactly so: the greater part of it must be intelligible to all: but in the very best there is often an undersong of sense, which none beside the poetical mind, or one deeply versed in its mysteries, can comprehend."; "1916, John Cowper Powys, “Oscar Wilde” in Suspended Judgments, New York: G. Arnold Shaw, p. 410, The mad smouldering lust which gives a sort of under-song of surging passion to the sophisticated sensuality of “Salome” …"; "Here we see this most reticent and mannerly of poets [i.e. Elizabeth Bishop] being compelled by the undeniable impetus of her art to break with her usual inclination to conciliate the social audience. [...] she usually limited herself to a note that would not have disturbed the discreet undersong of conversation between strangers breakfasting at a seaside hotel."figuratively

2. (obsolete) The burden of a song; the chorus; the refrain.Examples: "It is not hard to observe that David’s Allelujahs are more then his Hosannas; his thanks more then his suits. Oft-times doth he praise God when be begs nothing: seldome ever doth he beg that favour for which he doth not raise up his Soul to an anticipation of Thanks: neither is this any other then the universal under-song of all his Heavenly Ditties [...]"; "The Challenge to Damætas ſhall belong / Menalcas ſhall ſuſtain his under Song: / Each in his turn your tuneful numbers bring; / In turns the tuneful Muſes love to ſing."obsolete