Definition of "thirty-first" [thirty-first]

• The ordinal form of the number thirty-one, describing a person or thing in position number 31 of a sequence. (noun)
• One of thirty-one equal parts of a whole. (noun)

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• "Yet my college diploma says, “Given at Hempstead, New York, this thirty-first day of May, one thousand nine hundred AND eighty-nine.”"
• "In his thirty-first year as mayor, hubbard had forced Southenders to sell their houses to the city of Dearborn by using a variety of tactics."
• "The Green Movement is alive and well, and by some accounts gaining momentum, despite the poor showing on February 11th, the thirty-first anniversary of the Islamic Revolution."