thirty

American  

[thur-tee] / ˈθɜr ti /

noun

plural

thirties

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.

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

The chain aims to finish assembling drinks within two minutes and thirty seconds from the moment an order is placed.

From Los Angeles Times • Apr. 10, 2026

Southend-on-Sea City Council leader Daniel Cowan, who led on the five district proposal, said his team could draw on almost "thirty years" of already being a unitary authority.

From BBC • Mar. 25, 2026

The team analyzed the activity of hundreds of genes in about thirty cell clones taken from two primary colon tumors.

From Science Daily • Mar. 21, 2026

Former Marine Brian McGinnis began protesting around thirty minutes into the hearing.

From Salon • Mar. 5, 2026

“Is… is my pop lonely?” he asked, his voice soft and a little bit husky, like he’d come down with a cold in the last thirty seconds.

From "Not Nothing" by Gayle Forman