subtonic

The note immediately below the upper note of a musical scale.

(old-fashioned) An imperfectly articulated sound or utterance, as characterized by Dr. James Rush (Guide to Pronunciation, 1833).

(old-fashioned) Of or pertaining to imperfectly articulated sounds or utterances that are inaudible or barely audible, as characterized by Dr. James Rush (Guide to Pronunciation, 1833).