thirty

noun thir·ty \ ˈthər-tē \

Definition of thirty

plural thirties

1 :a number equal to three times 10 — see Table of Numbers

2 thirties plural :the numbers 30 to 39; specifically :the years 30 to 39 in a lifetime or century

3 :a sign of completion :end —usually written 30

wrote thirty on the last page of the story

4 :the second point scored by a side in a game of tennis

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thirtieth

play \-tē-əth\ adjective or noun

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thirty

adjective

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thirty

pronoun, plural in construction

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thirtyish

play \-ish\ adjective

See thirty defined for English-language learners

See thirty defined for kids

Examples of thirty in a Sentence

The temperature outside is in the high thirties.
He is in his thirties.

Recent Examples of thirty from the Web

The policy staff are also likely to predominantly be in their twenties or maybe thirties, something that shocks observers from abroad.

— ed kilgore, Daily Intelligencer, "Congress Is a Desert, Not a Swamp," 8 Aug. 2017
The Challenge XXX: Dirty Thirty airs Tuesdays (9 p.m. ET) on MTV.

— dana rose falcone, PEOPLE.com, "The Touching Way The Challenge Cast is Remembering Diem Brown 3 Years After Her Death," 7 Aug. 2017
Helen was in her early thirties, impossibly cool and tan on our gingham blanket, nodding along.

— lena dunham, Glamour, "Lena Dunham on How Her First Lilith Fair Taught Her There's More Than One Way of Being a Woman," 5 July 2017
Thirty minutes later, in an anticlimactic finale, the climbers threw a bag over Poncho, scooped him up and carried him back down the tree.

— james steinbauer, chicagotribune.com, "Odds stacked against those trying to find lost pets," 5 July 2017
The men in their thirties and forties who are single are so depressing!

— chris smith, Daily Intelligencer, "Single (Not that there’s anything wrong with that!)," 30 June 2017
Thirty miles away in Bear, Angie got a prescription after a car accident.

— mike newall, Philly.com, "Resisting temptation, when you're young and addicted to heroin in Kensington," 23 June 2017
Thirty degrees latitude, 90 degrees longitude are the coordinates of New Orleans.

— carlie kollath wells, NOLA.com, "Hurricane forecasters say no storms expected to form in Gulf of Mexico this week," 12 June 2017
In the nineteen-thirties, under Stalin, Soviet railway planners revived the proposal as part of the country’s industrialization drive, but the project went nowhere.

— joshua yaffa, The New Yorker, "Putin’s Shadow Cabinet and the Bridge to Crimea," 29 May 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'thirty.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of thirty

Middle English thritty, from thritty, adjective, from Old English thrītig, from thrītig group of 30, from thrīe three + -tig group of ten; akin to Old English tīen ten

NEW! Time Traveler

First Known Use: before 12th century

See Words from the same year