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nine·ty

(nīntē)

n. pl. nine·ties

1. The cardinal number equal to 9 × 10.

2. nineties

a. 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.

[Middle English ninti, from Old English nigontig; see new in the Appendix of Indo-European roots.]

ninety adj. & pron.

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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