ninety · number /ˈnɑɪnt.i/Full view
A2 the number 90
Dictionary examples:

eighty, ninety, a hundred

Ninety percent of the people surveyed were in favor.

Learner example:

Friday is the art class day. It is [in] ninety minutes. (Key English Test; A2; Turkish)

(be) in your nineties/90s
B2 to be aged between 90 and 99
Dictionary example:

He is in his nineties now.

the nineties/'90s
B2 the years 1990 through 1999
Dictionary example:

I spent most of the nineties traveling around the world.

Learner example:

Another aspect which shows us the danger that the car represents to human life in the nineties [is] pollution. (First Certificate in English; B2; Portuguese)

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