ninety · number /ˈnaɪn.ti/
A2 the number 90
eighty, ninety, a hundred
Ninety percent of the people surveyed were in favour.
It costs ninety euros, [a] good price. (Key English Test; A2; Catalan)
(be) in your nineties
B2 to be aged between 90 and 99
He is in his nineties now.
B2 the years from 1990-1999
I spent most of the nineties travelling around the world.
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)