ninety

1 of 3

noun (1)

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

ninetieth

2 of 3

adjective

nine·​ti·​eth ˈnīntē|ə̇th 

-ti|

1

: being number 90 in a countable series

the ninetieth day

see Table of Numbers

2

: being one of 90 equal parts into which something is divisible

a ninetieth share of the money

ninetieth

3 of 3

noun (2)

"

plural -s

1

: number 90 in a countable series

2

: the quotient of a unit divided by 90 : one of 90 equal parts of something

one ninetieth of the total

Examples of ninety in a Sentence

Noun (1)

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

Recent Examples on the Web

Noun

It is shared by parts of the Russian élite, and began to take shape after the collapse of the Soviet Union, becoming visible during the nineteen-nineties. — Isaac Chotiner, New Yorker, 18 June 2026

There seemed to be an endless, abundant supply, like tissues in a brand-new box, or how people thought about fossil fuels before the nineties—until suddenly there was just…nothing. — Literary Hub, 11 June 2026

Working well into his nineties, Le Parc proved her point, spending his last years experimenting with virtual reality. — News Desk, Artforum, 8 June 2026

All as much fans of soft-core nineties femme fatale films as experimental cinema. — Carly Tagen-Dye, PEOPLE, 3 June 2026

Word History

Etymology

Noun (1)

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

Adjective

Middle English nyntithe, from Old English nigontigotha, from nigontig ninety + -otha, -tha -th

First Known Use

Noun (1)

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