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 years on from those dramatic scenes in Edinburgh, the Commonwealth Games are once again being held in Scotland.

From BBC • Jun. 24, 2026

Forty percent of respondents in March said their company was using and planned to continue to use Gemini, up from 27% a year earlier.

From The Wall Street Journal • May 12, 2026

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

From BBC • Apr. 18, 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 or fifty or sixty Model 82958s were all deeply disappointed in Max at once.

From "The School for Whatnots" by Margaret Peterson Haddix