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

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

From Science Daily ● Jun. 10, 2026

But if anyone there didn’t already know who I was, they surely noticed the forty armed guards surrounding me.

From The Wall Street Journal ● Jun. 5, 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

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

Two other people lived in his home; they were his pretty, cheerful, innocent niece, about twenty, and his plump housekeeper, about forty, who was a good, friendly soul, with strong opinions about everything.

From "Adventures of Don Quixote" by Argentina Palacios

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

"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

"I won't be able to pay my rent, I will be in my forties and living back at home," he says.

From BBC ● Oct. 9, 2025

A man in his early forties, tall like nearly everyone on the boat ramp, he wore horn-rimmed spectacles behind which lurked sharp, penetrating eyes.

From "The Boys in the Boat: Nine Americans and Their Epic Quest for Gold at the 1936 Berlin Olympics" by Daniel James Brown