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

Forty people have drowned in heatwave-related deaths in France since last Thursday, Prime Minister Sebastien Lecornu said earlier this week.

From BBC • Jun. 25, 2026

Forty years later, Pope Pius XI, in “Quadragesimo Anno,” criticized concentrations of capital amid the widespread destitution during the Great Depression, but he also criticized the totalitarian responses sweeping Europe.

From The Wall Street Journal • Jun. 12, 2026

Forty teams from across the country were selected to compete.

From Los Angeles Times • May 17, 2026

Forty years later, the highly radioactive remains of the plant are in a warzone.

From BBC • Apr. 18, 2026

Forty minutes later, I have yet to touch pencil to paper.

From "Water for Elephants" by Sara Gruen