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

Ninety percent of it doesn’t land on anybody.

From Los Angeles Times • Apr. 1, 2026

Ninety percent of Iran's crude oil comes through a terminal on the island - transported through pipes from the mainland.

From BBC • Mar. 14, 2026

Ninety five percent of students chose to begin school later when given the option.

From Science Daily • Mar. 11, 2026

“Retaining coal might not be as big an issue as some suggest,” said Ninety One portfolio manager George Cheveley.

From The Wall Street Journal • Jan. 27, 2026

Ninety minutes above the river, I crested a broad ridge, passed a matrix of rock-walled yak corrals, and abrupdy found myself in downtown Namche Bazaar, the social and commercial hub of Sherpa society.

From "Into Thin Air" by Jon Krakauer