forty

American  

[fawr-tee] / ˈfɔr ti /

noun

plural

forties

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

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 artists had been booked to take part in its 12th year.

From BBC • Apr. 22, 2026

Forty years ago in February, Jackson wriggled free of her father Joe Jackson’s stifling management with the release of “Control.”

From Salon • Apr. 11, 2026

Forty years later, Kendrick Lamar borrowed Gadson’s intricate rhythm pattern for “Sing About Me, I’m Dying of Thirst,” from the rapper’s 2012 breakthrough album, “Good Kid, M.A.A.D City.”

From Los Angeles Times • Apr. 3, 2026

Forty percent of current workers will retire this decade.

From MarketWatch • Mar. 26, 2026

Forty minutes go by before anyone acknowledges my presence with more than a harried nod.

From "Nickel and Dimed: On (Not) Getting By in America" by Barbara Ehrenreich