ninety

American  

[nahyn-tee] / ˈnaɪn ti /

noun

plural

nineties

1. a cardinal number, ten times nine.

2. a symbol for this number, as 90 or XC.

3. a set of this many persons or things.

4. nineties, the numbers, years, degrees, or the like, from 90 through 99, as in referring to numbered streets, indicating the years of a lifetime or of a century, or degrees of temperature.

   His grandmother is in her nineties.

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adjective

1. amounting to 90 in number.

ninety British  

/ ˈnaɪntɪ /

noun

1. the cardinal number that is the product of ten and nine See also number

2. a numeral, 90, XC, etc, representing this number

3. something represented by, representing, or consisting of 90 units

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determiner

1. 1. amounting to ninety

      ninety times out of a hundred

   2. ( as pronoun )

      at least ninety are thought to be missing

Usage

Spelling tips for 90 The word ninety (90) is hard to spell because it can be hard to remember whether to include the e from nine when combining it with the suffix -ty. How to spell ninety: To spell ninety, you simply combine the base number (nine) with the suffix -ty, which means "multiple of 10." 9 x 10 = 90 or, in writing, nine + -ty = ninety.

Etymology

Origin of ninety

before 1000; Middle English nineti, Old English nigontig. See nine, -ty ¹

Explanation

Ninety is a number that's ten more than eighty and ten less than a hundred. Ninety is a pretty big number, but there's not much else to say about it. It's one of those numbers like "sixty" or "seventy" that is formed by attaching a number in the range of 1-9 and "ty" to represent values in the tens place starting with that number. And if you were alive during the nineties (the years from 1990-1999), you probably watched a lot of "Seinfeld" and "Friends."

Example Sentences

“Seventy to ninety percent of my life throughout those years was with him,” he says.

From Los Angeles Times • Sep. 10, 2025

That date can be set no sooner than ninety days from the date of Paxton’s request.

From Salon • Jun. 29, 2025

"We spend ninety minutes watching a game between the best writers of their time."

From BBC • Apr. 11, 2025

Dr Runsheng Yin has published over ninety peer-reviewed papers and served as an editor-in-chief for the international journal of Forest Policy and Economics.

From Science Daily • Feb. 26, 2024

He might like my descriptions of what I’ve seen on Sagan, but he’s known nothing but this ship for ninety percent of his life.

From "The Last Cuentista" by Donna Barba Higuera