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

Arbaeen, which means forty in Arabic, marks the 40th day of mourning for the martyrdom of Imam Hussein, the grandson of Prophet Mohammed and a founding figure in Shia Islam.

From Barron's ● Aug. 1, 2026

For forty years, developed economies largely rewarded capital over labor.

From MarketWatch ● Jul. 24, 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

In 1976, scientists realized that γ Cas emits X-rays about forty times stronger than similar stars.

From Science Daily ● Mar. 25, 2026

I dare to look up, only to see at least forty creatures in the branches above us, whistling and crying.

From "Kwame Crashes the Underworld" by Craig Kofi Farmer

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

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

Goldman was from Queens, a streetwise, muscled Air Force veteran in his forties, and I considered him a stalwart.

From "Newjack: Guarding Sing Sing" by Ted Conover