·noun An interval containing an octave and a second.
II. Ninth ·noun A chord of the dominant seventh with the ninth added.
III. Ninth ·adj Following the eight and preceding the tenth; coming after eight others.
IV. Ninth ·adj Constituting or being one of nine equal parts into which anything is divided.
V. Ninth ·noun The quotient of one divided by nine; one of nine equal parts of a thing; the next after the eighth.