/ ˈnaɪnti; NAmE /
1.
number 90
2.
noun the nineties [ pl. ] numbers, years or temperatures from 90 to 99 :
The temperature must be in the nineties today.
► nine·ti·eth / ˈnaɪntiəθ; NAmE / ordinal number , noun
HELP NOTE : There are examples of how to use ordinal numbers at the entry for fifth .
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IDIOMS
- in your nineties
- ninety-nine times out of a hundred
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WORD ORIGIN
Old English nigontig .