In music, a ninth is a compound interval consisting of an octave plus a second. Like the second, the interval of a ninth is classified as a dissonance in common practice tonality. Since a ninth is an octave larger than a second, its sonority level is considered less dense.

What does ninth mean?

adjective. (usually prenominal) coming after the eighth in counting order, position, time, etc; being the ordinal number of nine. Often written: 9th. (as noun)he came on the ninth; ninth in line.

What is a ninth in maths?

one of nine equal or nearly equal parts of an object, quantity, measurement, etc. b. (as modifier): a ninth part. 2. ( Mathematics) the fraction equal to one divided by nine ()