thirty

American  

[thur-tee] / ˈθɜr ti /

noun

• thirties
  plural

1. a cardinal number, 10 times 3.

2. a symbol for this number, as 30 or XXX.

3. a set of this many persons or things.

4. Printing, Journalism. 30-dash.

5. thirties, the numbers, years, degrees, or the like, from 30 through 39, as in referring to numbered streets, indicating the years of a lifetime or of a century, or referring to degrees of temperature.

   He works in the East Thirties. She must be in her thirties. The temperature was in the thirties yesterday.

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adjective

1. amounting to 30 in number.

thirty British  

/ ˈθɜːtɪ /

noun

1. the cardinal number that is the product of ten and three See also number

2. a numeral, 30, XXX, etc, representing this number

3. (plural) the numbers 30–39, esp the 30th to the 39th year of a person's life or of a century

4. the amount or quantity that is three times as big as ten

5. something representing, represented by, or consisting of 30 units

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determiner

1. 1. amounting to thirty

      thirty trees

   2. ( as pronoun )

      thirty are broken

Usage

Spelling tips for 30 The word thirty (30) is hard to spell because it doesn’t simply combine the spelling of the base number (three) with the suffix -ty, as is done in other easy-to-remember spellings like sixty and seventy.  How to spell thirty: When three is combined with suffixes, it transforms from three (a cardinal number) to third (an ordinal number). Then, the d is dropped: thirteen (not thirdteen); thirty (not thirdty). Remember: there's no d in thirty.

Other Word Forms

Noun Inflected Forms

• thirties
  plural

Etymology

Origin of thirty

before 900; Middle English thritty, Old English thrītig, equivalent to thrī three + -tig -ty ¹; cognate with Dutch dertig, German dreissig, Old Norse thrjātīu

Example Sentences

See Examples For:

thirty thirties

Across the globe, bond yields are setting new highs with 10-year benchmarks at their steepest for thirty years in Japan, fifteen years for Germany and 18 years in the U.K.

From MarketWatch ● Sep. 1, 2026

It wants a chair and thirty quiet minutes.

From Salon ● Aug. 11, 2026

The Nikkei 225 gained 38% as the Bank of Japan tightened rates, leading to the highest interest rates in over thirty years.

From Barron's ● Jun. 30, 2026

And they recognized that Charlie, barely thirty years old when he was killed, was still learning and evolving, as we all do over the course of our lives.

From The Wall Street Journal ● Jun. 5, 2026

Sue, Bruce, and Dan carried Brian to a demolished cabin thirty feet away.

From "Mountain of Fire" by Rebecca E. F. Barone

Another witness, in his thirties, corroborated reports of an explosion.

From Barron's ● Aug. 30, 2026

The man is thought to have been in his thirties or forties, officials added.

From BBC ● Jul. 30, 2026

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

But researchers are seeing a troubling shift in younger people, with more cases now appearing in adults under 50, including some in their thirties.

From Science Daily ● May 15, 2026

Their lives were at sea, together and apart, as they passed from their twenties to their early thirties.

From "Zeitoun" by Dave Eggers