\Sub*ton"ic\, a. (Phonetics)
Applied to, or distinguishing, a speech element consisting of
tone, or proper vocal sound, not pure as in the vowels, but
dimmed and otherwise modified by some kind of obstruction in
the oral or the nasal passage, and in some cases with a
mixture of breath sound; -- a term introduced by Dr. James
Rush in 1833. See Guide to Pronunciation, [sect][sect]155,
199-202.

\Sub*ton"ic\, n.
1. (Phonetics) A subtonic sound or element; a vocal
   consonant, as b, d, g, n, etc.; a subvocal.
2. (Mus.) The seventh tone of the scale, or that immediately
   below the tonic; -- called also {subsemitone}.