in Music, a name given by M. Rameau to the fourth note of the tone, which of consequence is the same interval from the tonic when descending as the dominant in rising. This denomination arises from the affinity which this author finds by inversion between the minor mode of the subdominant and the major mode of the tonic.

SUBDUPLE ratio, is when any number or quantity is contained in another twice. Thus 3 is said to be subduple of 6, as 6 is duple of 3. See Ratio.