A Dictionary of Music and Musicians/Supertonic

SUPERTONIC. The second note of the scale upwards, as D in the key of C. It is brought into much prominence in modern music as the dominant note of the dominant key. The strong tendency to find the chief balance and antithesis in that key, and to introduce the second subject of a movement in it, as well as the tendency to make for that point even in the progress of a period, necessarily throws much stress upon the root-note of the harmony which leads most directly to its tonic harmony, and this is the dominant of the new key or supertonic of the original one. It has consequently become so familiar, that its major chord and the chord of the minor seventh built upon it, although chromatic, are freely used as part of the original key, quite irrespective of the inference of modulation which they originally carried. Some theorists recognise these chords as part of the harmonic complement of the key, and consequently derive several of the most characteristic and familiar chromatic combinations from the supertonic root.

[ C. H. H. P. ]