ninety

noun

nine·​ty ˈnīn-tē 

plural nineties

1

: a number equal to nine times 10 see Table of Numbers

2

nineties plural : the numbers 90 to 99

specifically : the years 90 to 99 in a lifetime or century

She's in her nineties.

ninetieth

ˈnīn-tē-əth 

adjective or noun

ninety adjective

ninety pronoun, plural in construction

Examples of ninety in a Sentence

During the nineties, he was going to college and working part-time.

Recent Examples on the Web

Advertisement Indians and Pakistanis, who remember a life before the Partition, before the borders, are in their nineties and dying fast. —Sam Dalrymple, Time, 14 July 2025

Kartal, who was born in 2001, was wearing a boxy outfit inspired by the nineties, one of her favorite historical periods. —Sam Knight, New Yorker, 12 July 2025

By the late nineties, relatively wealthier nations had childhood-vaccination rates of more than ninety per cent, and were seeing few cases of vaccine-preventable diseases. —Rivka Galchen, New Yorker, 27 June 2025

In the nineties, MAC Cosmetics was the new kid on the block. —Essence, 24 June 2025

Word History

Etymology

Middle English ninety, adjective, from Old English nigontig, short for hundnigontig, from hundnigontig, noun, group of 90, from hund-, literally, hundred + nigon nine + -tig group of 10; akin to Old English tīen ten

First Known Use

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

Phrases Containing ninety

• ninety-nine times out of a hundred
• ninety/ninety-nine percent of the time

Kids Definition

ninety

noun

nine·​ty ˈnīnt-ē 

plural nineties

1

: a number equal to nine times 10 see number

2

plural : the numbers 90 to 99 and specifically the years 90 to 99 in a lifetime or century

ninetieth

-ē-əth 

adjective or noun

ninety adjective or pronoun