ninety
n.n. the number 90. It comes after eighty-nine and before ninety-one.
n. the cardinal number equivalent to the product of nine and ten. Functions as both a noun and a determiner depending on the syntactic context.
My grandfather is ninety years old.
The speed limit on this stretch of the highway is ninety kilometers per hour.
The temperature in the desert rose to nearly ninety degrees by midday, forcing the researchers to seek shelter until the sun began its descent.
From Middle English nynty, nynety, from Old English hundniġontiġ, from Proto-Germanic *newuntēhundą (“ninety”), equivalent to nine + -ty. Cognate with Scots nynty, nynety (“ninety”), Saterland Frisian njuugentich (“ninety”), West Frisian njoggentich (“ninety”), Dutch negentig (“ninety”), German Low German negentig (“ninety”), German neunzig (“ninety”), Swedish nittio (“ninety”), Norwegian Bokmål nitti (“ninety”), Norwegian Nynorsk nitti (“ninety”), Icelandic níutíu (“ninety”).
When used as a determiner, it precedes the noun it modifies. In its plural form, 'nineties', it refers to a decade or a range of temperatures.
nintyninetyLearners often mistakenly drop the 'e' from 'nine' when adding the suffix '-ty'.