descant

descant is a Noun

Definition:

[1] Originally, a double song; a melody or counterpoint sung above the plain song of the tenor; a variation of an air; a variation by ornament of the main subject or plain song.

[2] The upper voice in part music.

[3] The canto, cantus, or soprano voice; the treble. Grove. Twenty doctors expound one text twenty ways, as children make descant upon plain song. Tyndale. She [the nightingale] all night long her amorous descant sung. Milton.

[4] A discourse formed on its theme, like variations on a musical air; a comment or comments. Upon that simplest of themes how magnificent a descant! De Quincey.