thirty

[ thur-tee ]

noun

, plural thir·ties.

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.

adjective

1. amounting to 30 in number.

thirty

/ 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

determiner

1. 1. amounting to thirty

      thirty trees

   2. ( as pronoun )

      thirty are broken

Word History and Origins

Origin of thirty¹

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

Word History and Origins

Origin of thirty¹

Old English thrītig; see three , -ty ¹

Example Sentences

Meanwhile, Mahama spent his twenties and thirties studying - he got a Communication Studies degree from the University of Ghana before studying at Moscow's Institute of Social Sciences.

From BBC

The officer, a constable aged in his thirties, was arrested on Tuesday in Gloucestershire by counterterrorism police, who said the suspected support "relates to activity online".

From BBC

BBC News has spoken to two women and two men in their early thirties - the average age at which people in England and Wales become parents - to get their thoughts on the issue.

From BBC

The idea of having kids in my twenties and thirties just seemed crazy to me.

From Salon

Around thirty people have been evacuated from a residential tower block in east London after a fire broke out.

From BBC

How Do You Spell 30?

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.