thir·​ty | \ ˈthər-tē How to pronounce thirty (audio) \
plural thirties

Definition of thirty

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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Other Words from thirty

thirtieth \ ˈthər-​tē-​əth How to pronounce thirty (audio) \ adjective or noun
thirty adjective
thirty pronoun, plural in construction
thirtyish \ ˈthər-​tē-​ish How to pronounce thirty (audio) \ adjective

Examples of thirty in a Sentence

The temperature outside is in the high thirties. He is in his thirties.
Recent Examples on the Web Crutchfield is in her early thirties, just about old enough to have listened as a kid and a teenager to Apple’s music and to that of similar artists in Apple’s generation, roughly clustered around events such as the early iterations of Lilith Fair. Helena Fitzgerald,, 28 Apr. 2020 In her early thirties, Perkins witnessed the Triangle Shirtwaist Factory fire, which killed 146 garment workers — mostly women and girls. Annalyn Kurtz, CNN, 10 Apr. 2020 On January 1, 1984, a British woman in her early thirties named Tina Brown was appointed editor-in-chief of Newhouse’s reboot of Vanity Fair. Kyle Chayka, The New Republic, 21 Oct. 2019 Her break from Bill is the choice that enables her to become an accomplished and well-connected law professor at Northwestern, politically one to watch in her thirties, and a United States senator by her forties. Laura Marsh, The New Republic, 19 May 2020 Kadolph tried suppressing her childhood memories, but her battle with anorexia continued into her thirties. Wire Service, The Mercury News, 11 July 2019 By her mid-thirties, Gornick identified with the novel’s hero, Paul Morel, who does the desiring. Sophie Pinkham, The New Republic, 1 May 2020 One of those who left the Olive Tree religious movement was a Korean war veteran in his mid-thirties who had spent 10 years worshiping there. Joshua Berlinger, CNN, 6 Mar. 2020 Monteiro is in his mid-thirties, with thick black hair that’s going silver around his ears. Brian Merchant, Harper's magazine, 31 Dec. 2019

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.

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First Known Use of thirty

before the 12th century, in the meaning defined at sense 1

History and Etymology for 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

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Time Traveler for thirty

Time Traveler

The first known use of thirty was before the 12th century

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Statistics for thirty

Cite this Entry

“Thirty.” Dictionary, Merriam-Webster, Accessed 13 Jun. 2021.

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More Definitions for thirty



English Language Learners Definition of thirty

: the number 30
: the numbers ranging from 30 to 39
: a set of years ending in digits ranging from 30 to 39


thir·​ty | \ ˈthər-tē How to pronounce thirty (audio) \

Kids Definition of thirty

 (Entry 1 of 2)

: being three times ten



Kids Definition of thirty (Entry 2 of 2)

: three times ten : 30

More from Merriam-Webster on thirty

Nglish: Translation of thirty for Spanish Speakers

Britannica English: Translation of thirty for Arabic Speakers


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