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

Finally, a man in his thirties, with head shaved, walks toward me. —Joseph Bien-Kahn, Rolling Stone, 3 Nov. 2024

Judge and Cole are both in their thirties and have likely peaked as players. —Tony Blengino, Forbes, 1 Nov. 2024

Former Saturday Night Live writer Lauren Pomerantz penned the script for the film based on her own experience of coming out in her thirties. —Jennifer M. Wood, WIRED, 29 Oct. 2024

Surprise, surprise, an actress in her thirties coming off a CW teen drama wasn’t exactly in high demand. —Gillian Telling, People.com, 16 Oct. 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