What does ninety mean?
Ninety is the cardinal number 90, equivalent to nine groups of ten. It commonly appears in quantities, measurements, ages, percentages, and temperatures, as in “ninety percent” or “ninety degrees.” The word can also designate a person of that age, although a form such as “a ninety-year-old” is usually clearer when the age is important. In the plural, “nineties” with “the” refers either to a decade from 1990 to 1999 or, more generally, to people who are between ninety and ninety-nine years old. Ninety is notable within the English numeral system because its formation does not follow the transparent tens pattern used by numbers such as twenty, thirty, and forty. Instead, it belongs to the irregular group built from nine. The word has long been established in English and is especially useful when expressing exact quantities, ages, scores, and proportions.
The cardinal number equal to nine times ten.
"The bridge is ninety metres long."
Often used attributively before a noun, as in “ninety dollars” or “ninety degrees.”
A person who is ninety years old, or a group consisting of ninety people or things.
"The portrait depicts a ninety-year-old surrounded by her grandchildren."
As an age label, “ninety-year-old” is often more explicit and natural.
Usually takes the definite article, as in “the nineties.” It refers to the decade from 1990 to 1999 or to people between ninety and ninety-nine years old.
"The family moved to the city in the mid-nineties."
Ninety belongs to a small family of English numbers whose names refuse to follow their own counting rules: nine, ten, eleven, and twelve are irregular, while thirteen through nineteen add “teen.”
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does ninety come from?
Ninety derives from Old English nīnig, an inherited Germanic numeral meaning “nine tens.” It is historically related to nine, although the formation of ninety reflects an older irregular development within the English and Germanic numeral systems. Modern forms in languages such as German, Dutch, and Old Norse show comparable numerals based on the word for nine combined with a tens-forming element.
How ninety is actually used
The exact pronunciation of the final syllable varies: some speakers say /ˈnaɪnti/, while others, particularly in British English, say /ˈnaɪntə/. When referring to the decade, the usual form is “the nineties,” and a decade may be described as “the early, mid-, or late nineties.”