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

Ah, the nostalgic nineties, that notorious decade that's now being strip-mined for its influential music, funky fashion, dance moves, comics, movies, and television. —Jeff Spry, Space.com, 29 Jan. 2026

By the nineties, there were about six hundred thousand Unificationists in Japan, twice as many as in Korea. —E. Tammy Kim, New Yorker, 26 Jan. 2026

The British rock band enjoyed one of the greatest runs ever in the seventies, eighties, and nineties, and though the group hasn’t delivered a new full-length in decades, Queen’s songs and albums regularly continue to rank as top sellers in many major markets. —Hugh McIntyre, Forbes.com, 16 Jan. 2026

Smith launched their original Slider sunglasses in 1995, leaning into the nineties silhouette and beefing it up with the first patented dual-lens interchangeable system. —Lily Ritter, Outside, 14 Jan. 2026

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