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

Butler has garnered a list of nagging injuries over the years that could present a challenge to a Lakers roster featuring two leaders in their thirties who have also collected laundry lists of injuries over the years. —Stephan Pechdimaldji, Newsweek, 14 Dec. 2024

For women in their thirties, the absolute risk increased from one in 204 to 1.4 in 204. —Dominique Fluker, Essence, 28 Oct. 2024

Our next passengers, a couple that look to be in their early thirties, get in at 1:35 pm in front of the Fairmont Hotel (where, three months later, a robotaxi will get stuck in the path of Kamala Harris’ motorcade). —Wired Staff, WIRED, 20 Nov. 2024

Both of them are in their late thirties and the matchmakers have a lot of confidence that this couple will last—and fans do too! —Lea Veloso, StyleCaster, 15 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