from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The cardinal number equal to 9 × 10.
  • n. A decade or the numbers from 90 to 99: My grandparents are in their nineties. During the heat wave, the temperature stayed in the nineties.
  • n. The decade from 90 to 99 in a century.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The cardinal number occurring after eighty-nine and before ninety-one, represented in Roman numerals as XC and in Arabic numerals as 90.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Nine times ten; eighty-nine and one more.
  • n. The sum of nine times ten; the number greater by a unit than eighty-nine; ninety units or objects.
  • n. A symbol representing ninety units, as 90 or xc.

from The Century Dictionary and Cyclopedia

  • Nine times ten; one more than eighty-nine, or ten less than a hundred: a cardinal numeral.
  • n. The sum of ten nines, or nine tens; nine times ten.
  • n. A symbol representing ninety units, as 90, or XC, or xc.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. being ten more than eighty
  • n. the cardinal number that is the product of ten and nine


Middle English ninti, from Old English nigontig; see newn̥ in Indo-European roots.
(American Heritage® Dictionary of the English Language, Fourth Edition)



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