SUBTONIC n. 3 definitions
A subtonic sound or element; a vocal consonant, as b, d, g, n, etc.; a subvocal.
KEY n.
r three, dominant or five, subdominant or four, submediant or six, supertonic or two, and subtonic or seven. Chromatic tones are temporary members of a key, under such names as " sharp four," "flat seven," etc. Scales and tunes of every variety are made from the tones of a key.