FOURTH n. 4 definitions
a semitone, embracing four diatonic degrees of the scale; the subdominant of any key. The Fourth, specifically, un the United States, the fourth day of July, the anniversary of the declaration of American independence; as, to celebrate the Fourth.
ATTENDANT a.
with, the principal key; those, namely, of its fifth above, or dominant, its fifth below (fourth above), or subdominant, and its relative minor or major.