I. ˈnīn(t)th adjective
Etymology: Middle English nynthe, adjective & noun, alteration (influenced by nyne, nigen, nine) of nithe, from Old English nigotha (akin to Old Saxon nigutho, Middle Low German negede ), from nigon nine + -otha, -tha -th — more at nine
1. : being number nine in a countable series
the ninth day
— see number table
2. : being one of nine equal parts into which something is divisible
a ninth share of the money
II. noun
( plural ninths -īn(t)s, -īn(t)ths)
1. : number nine in a countable series
the ninth of the month
2. : the quotient of a unit divided by nine : one of nine equal parts of something
one ninth of the total
3.
a. : a musical interval embracing an octave and a second
b. : a tone at this interval
c. : ninth chord
III. adverb
1. : in the ninth place
2. : with eight exceptions
the nation's ninth largest city