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

The underwater life is still with her, in her thirties: the smell of chlorine, nylon straps digging into shoulders, hair clumped into icicles after predawn workouts in a Toronto suburb. —The New Yorker, 24 Dec. 2024

Diaz turns 28 next month so a new deal would take him into his thirties, and the club’s owner, FSG, has been very careful with similar offers in the past for players in their peak years. —Gregg Evans, The Athletic, 24 Dec. 2024

What's New Portions of Northern Florida and southern Georgia may see temperatures dip into the low thirties over the weekend, according to the National Weather Service (NWS). —Gord Magill, Newsweek, 20 Dec. 2024

Add to that my uncanny ability to only fall for guys who wouldn’t or couldn’t love me back, and well, my twenties, thirties, and forties were a blur. —Essence, 17 Dec. 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