The ordinal form of the number eighty-nine, describing a person or thing in position number 89 of a sequence.(noun)
One of eighty-nine equal parts of a whole.(noun)
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Use "eighty-ninth" in a sentence
"Then, the day before her eighty-ninth birthday, she woke as curious, as alive, and as expectant as she had ever been."
"The front of the darwaza would also be built of the red sandstone so prolific in the quarries around Agra but inlaid with white marble, into which would be carved, in calligraphic script, the eighty-ninth sura from the Quran, which invited believers to step into Paradise."
"She died of a heart attack in Princeton, New Jersey, on June 2, 1967, a day after her eighty-ninth birthday."