nine·ty  (n īn t ē)
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n. pl. nine·ties 1. The cardinal number equal to 9 × 10. 2. ninetiesa. 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. b. often Nineties The decade from 90 to 99 in a century.
ninety adj. & pron. |
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
Indo-European Roots
Semitic Roots
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.
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