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

The premium attached to European defense plays in the current environment are reflected in a price-to-earnings multiple of almost forty times for 2026, more than double that of the overall market.

From MarketWatch • Mar. 11, 2026

"They took away valuables -- my radio, my phone, and forty head of livestock" from the village, he said, not daring to name those responsible.

From Barron's • Feb. 26, 2026

James Hankins is leaving Harvard after forty years as a history professor.

From The Wall Street Journal • Dec. 29, 2025

After nearly forty years of electoral service in Congress, former House Speaker Nancy Pelosi may be on her way out.

From Salon • Nov. 3, 2025

Three days later we moved to Ikuma, forty miles from the seacoast.

From "Black Star, Bright Dawn" by Scott O'Dell