ninety

ninety — noun

1. the number that comes after eighty-nine and before ninety-one, used when countin

1.nounA1
Definition

the number that comes after eighty-nine and before ninety-one, used when counting or saying how many of something there are

Example

Kevin saved ninety dollars from his summer job to buy a new bicycle.

quantity: ninety + countable noun (dollars)

The temperature outside reached ninety degrees by noon today.

measurement: ninety degrees (temperature)

Common collocations
  • ninety percent
  • ninety degrees
  • ninety out of
  • turn ninety
  • ninety-nine

Grammar Patterns

ninety + noun (plural)

ninety out of + number

Usage Note

When writing compound numbers from ninety-one to ninety-nine as words, use a hyphen between 'ninety' and the unit (e.g., ninety-seven, ninety-two).

Common Mistakes

I am ninety years.
I am ninety years old.
When talking about age, you need 'years old' or 'years of age' after the number.
Ninety peoples came to the party.
Ninety people came to the party.
'People' is already plural; do not add an 's'.

2. the written symbol or name '90' treated as a thing — for example, a mark on a pa

2.nounA1
Definition

the written symbol or name '90' treated as a thing — for example, a mark on a page or the name of a number in a maths problem

Example

The child drew a large ninety on the paper with a bright blue crayon.

countable: a ninety (physical symbol)

If you turn a ninety upside down, it looks a lot like the number six.

Grammar Patterns

a ninety

the ninety

a + number + ninety

Usage Note

Unlike the cardinal sense (sense 1), this noun sense treats 'ninety' as a countable object — you can say 'a ninety' or 'the ninety'. It refers to the numeral as a physical or written thing rather than a quantity.

3. the set of whole numbers from ninety up to ninety-nine, used especially when des

3.nounA2
Definition

the set of whole numbers from ninety up to ninety-nine, used especially when describing a person's age, the temperature, a score, or a period of ten years in a century

Example

Ayesha's grandmother is in her nineties and still knits sweaters for the family every winter.

age range: in one's nineties

Temperatures in the nineties are common in Taipei during July and August.

temperature range: in the nineties

Common collocations
  • in one's nineties
  • in the nineties
  • low nineties
  • high nineties
  • mid-nineties

Grammar Patterns

in the nineties

in one's nineties

the nineties (as a decade)

Usage Note

This sense always uses the plural form 'nineties'. The meaning changes by context: 'in one's nineties' = age 90–99; 'in the nineties' = temperature 90–99°F or the 1990s decade.

Common Mistakes

My grandmother is in her ninety.
My grandmother is in her nineties.
Use the plural form 'nineties' when referring to an age range or temperature range.

Word family

  • nine
    numberA1
  • nineteen
    numberA1
  • ninetieth
    adjectiveA2
  • nineties
    nounA2

Synonym discussion

Sense: noun/1

'Ninety' (90) is a cardinal number — it tells you exactly how many. 'Nineties' is the plural form used for a range (90–99) or a decade, as in 'the nineties.' 'Ninetieth' (90th) is the ordinal form, used for order or position, such as 'her ninetieth birthday.' 'Nineteen' (19) is a different number entirely and is a common source of confusion — learners sometimes accidentally write 'ninety' when they mean 'nineteen' and vice versa. Remember: 'ninety' has a 'ty' sound at the end like 'twenty,' while 'nineteen' ends with 'teen' like 'thirteen.'

ninety ↗ninetiesninetiethnineteen ↗

Common collocations

Nouns

  • ninety percent
  • ninety degrees
  • ninety-nine

Phrases

  • in one's nineties
  • the nineties (decade)

Prepositions

  • in the nineties
  • out of ninety

Etymology

Old EnglishMiddle EnglishEnglish

Ninety comes from Old English 'hundnigontig', which was formed by combining 'nigon' (meaning 'nine') and '-tig' (meaning 'a group of ten'). Over time the 'hund-' prefix was dropped, and the word gradually changed into the modern form 'ninety'.