forty

American  

[fawr-tee] / ˈfɔr ti /

noun

• forties
  plural

1. a cardinal number, ten times four.

2. a symbol for this number, as 40 or XL or XXXX.

3. a set of this many persons or things.

4. forties, the numbers, years, degrees, or the like, from 40 through 49, as in referring to numbered streets, indicating the years of a lifetime or of a century, or degrees of temperature.

   His office is in the West Forties. Her parents are in their forties. The temperature will be in the forties.

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adjective

1. amounting to 40 in number.

forty British  

/ ˈfɔːtɪ /

noun

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

2. a numeral, 40, XL, etc, representing this number

3. something representing, represented by, or consisting of 40 units

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determiner

1. 1. amounting to forty

      forty thieves

   2. ( as pronoun )

      there were forty in the herd

Other Word Forms

Noun Inflected Forms

• forties
  plural

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Etymology

Origin of forty

before 950; Middle English fourti, Old English fēowertig (cognate with Old Frisian fiuwertich, Old High German fiorzug, German vierzig ). See four, -ty ¹

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Explanation

Whether you call it 40 or XL, you're talking about forty: the number between thirty-nine and forty-one. If you’ve ever seen the Roman numeral XL, that means forty, since X equals ten, L equals 50 and if you put the X before the L it means L minus X or 50 minus 10 — which is 40. This number comes up in the Bible a lot, especially when the earth is said to have been flooded for forty days and forty nights. Most people are not that thrilled to turn 40 years old: it means they're middle-aged.

Example Sentences

See Examples For:

forty forties

"We're thrilled to have Lena turn her gaze from the tumult of one's twenties to the milestone of turning forty," Amy Gravitt, executive vice-president of HBO programming, said.

From BBC ● Oct. 14, 2026

One reason to be confident that AI’s market-beating odds won’t improve in any lasting way is a famous article written nearly forty years ago by William Sharpe, the 1990 Nobel laureate in economics.

From MarketWatch ● Aug. 25, 2026

When the list expanded to forty words, accuracy dropped to just 15%.

From Science Daily ● Jun. 10, 2026

Birol told Australian media that at least forty energy assets across the region had been "severely or very severely damaged" in the conflict.

From Barron's ● Mar. 23, 2026

Now I was due at the store in forty minutes, and there was nothing to do but break it to her outright.

From "The Red Car to Hollywood" by Jennie Liu

She now plans to get one every year of her forties.

From BBC ● Aug. 10, 2026

Nasser Al-Dhafiri, a civil servant in his forties, described "immense psychological pressure" on ordinary people as the attacks sparked fears of electricity outages.

From Barron's ● Jul. 21, 2026

"We're not cutting the trees. We just pick up whatever wood's already on the ground to use for the fire," said Nafisa, a woman in her forties navigating the dry grasslands.

From Barron's ● Feb. 19, 2026

Even though McDaniels is still in his forties, he has been working in the same system long enough that he seems to know instantly how to address any situation.

From The Wall Street Journal ● Feb. 4, 2026

Those had been the days back then in the postwar boom of the forties and fifties.

From "Friday Night Lights: A Town, A Team, And A Dream" by H.G. Bissinger

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