Definition of ninetieth in English:

ninetieth

ordinal number

  • 1Constituting number ninety in a sequence; 90th.

    ‘her ninetieth birthday celebration’
    ‘a goal in the ninetieth minute’
  • 2Each of ninety equal parts into which something is or may be divided.

    ‘a series of lines a ninetieth of an inch apart’

Pronunciation

ninetieth

/ˈnʌɪntɪəθ/