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

Tariq, an activist in her early thirties, said that in the days since the army retook the city from the RSF, she's enjoyed doing the small, ordinary things that were impossible when Khartoum was a conflict zone. —Emmanuel Akinwotu, NPR, 6 Apr. 2025

Đặng Thơ Thơ, in her thirties and in a new country, was able to turn what was just a hobby in Vietnam into her occupation in the United States. —Victoria Le, Oc Register, 3 Apr. 2025

In fiscal year 2024, nearly three hundred thousand students and borrowers submitted complaints, more than double the previous year. Gittleman, who is in her early thirties, worked in the Ombudsman Group, the watchdog of the F.S.A. —E. Tammy Kim, New Yorker, 1 Apr. 2025

Now in her thirties and wrapping up a master's degree in speech-language pathology, Spudich found the timing of her discovery poignant. —Ron Estes, MSNBC Newsweek, 30 Mar. 2025

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

Rhymes for thirty

• birdie
• gurdy
• purdy
• sturdy
• wordy

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