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

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

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

That changed when an international team returned to the site using modern technology unavailable to scientists forty years earlier.

From Science Daily ● May 20, 2026

In our town, we’re told in the new LA28 announcement of the Cultural Olympiad: “It’s been forty years. Los Angeles is ready to do it again.”

From Los Angeles Times ● May 11, 2026

The premium attached to European defense plays in the current environment are reflected in a price-to-earnings multiple of almost forty times for 2026, more than double that of the overall market.

From MarketWatch ● Mar. 11, 2026

James Hankins is leaving Harvard after forty years as a history professor.

From The Wall Street Journal ● Dec. 29, 2025

Kuboyama died of liver failure at the age of forty, six months after coming home.

From "Fallout: Spies, Superbombs, and the Ultimate Cold War Showdown" by Steve Sheinkin

Confirmed traffic through the strait fell to just 10 ships Monday, according to ship-tracking firm Kpler, compared with levels in the thirties and forties early last week.

From The Wall Street Journal ● Jul. 14, 2026

"I had gone to bed a bit late, but the air-raid sirens woke me up, leaving me feeling anxious," said Nawal Saad, a Bahraini civil servant in her forties.

From Barron's ● Jul. 8, 2026

The man, who is in his forties, cannot be named for legal reasons.

From BBC ● Feb. 23, 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

Siddhartha himself, who was only in his forties, had noticed gray hairs here and there in his black hair.

From "Siddhartha" by Hermann Hesse