thirty

noun

thir·​ty ˈthər-tē 

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

thirtieth

ˈthər-tē-əth 

adjective or noun

thirty adjective

thirty pronoun, plural in construction

thirtyish

ˈthər-tē-ish 

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

In my thirties, the combination of fresh inflammation and scar tissue from a teenage surgery had blocked up my bowel. —Andrew Chapman, Longreads, 18 Apr. 2024

But Caron, who is in his late thirties and grew up exploring the woods of South Carolina, prefers a leave-no-trace approach. —Anna Wiener, The New Yorker, 15 Apr. 2024

And then both of our careers totally took off in our late thirties. —Hannah Sacks, Peoplemag, 23 Feb. 2024

Sparhawk, who was diagnosed with severe A.D.H.D. and borderline personality disorder in his late thirties, now believes that his father had similar problems. —Justin Taylor, The New Yorker, 11 Apr. 2024

More than half of U.S babies born in 2023 had mothers who were older than 30, according to Centers for Disease Control and Prevention data, and birth rates for women in their thirties are at higher levels than in the past four decades, according to a University of Rochester Medical Center report. —Sunny Nagpaul, Fortune, 11 Apr. 2024

The actual connection between the two young girls (now women in their thirties and forties) isn’t all that hard to parse given the details laid out, and the movie is quick to reveal it too. —Siddhant Adlakha, Variety, 18 Mar. 2024

Carlos and Laz are both in their thirties, and talked online for years before coming out to Slab City together. —Jonah Gercke, SPIN, 15 Mar. 2024

In a modern world that moves so fast and in such a volatile way, some might feel paralyzed by the idea of making such a profound change in their late thirties. —Geoffrey Bunting, Rolling Stone, 29 Feb. 2024

Word History

Etymology

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

First Known Use

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

Phrases Containing thirty

• thirty-eight
• thirty-second note
• thirty-second rest
• thirty-thirty
• thirty-three
• thirty-two
• thirty-twomo

Kids Definition

thirty

noun

thir·​ty ˈthərt-ē 

plural thirties

1

: a number equal to three times 10 see number

2

plural : the numbers 30 to 39

especially : the years 30 to 39 in a lifetime or century

thirtieth

-ē-əth 

noun or adjective

thirty adjective or pronoun