nine·ty 
/ˈnaɪnti/ noun
plural nine·ties /ˈnaɪnti/ noun 1 [count] : the number 90 2 nine*ties [plural] a : the numbers ranging from 90 to 99
▪ temperatures in the nineties ▪ It was priced in the low nineties. [=its price was about $91,000–$93,000]
b : a set of years ending in digits ranging from 90 to 99
▪ I studied there in the nineties. [=between 1990–1999] ▪ During the nineties, he was going to college and working part-time. ▪ He lived into his nineties. [=he was over ninety years old when he died]
▪ temperatures in the nineties ▪ It was priced in the low nineties. [=its price was about $91,000–$93,000]
b : a set of years ending in digits ranging from 90 to 99
▪ I studied there in the nineties. [=between 1990–1999] ▪ During the nineties, he was going to college and working part-time. ▪ He lived into his nineties. [=he was over ninety years old when he died]
— nine·ti·eth /ˈnaɪntijəθ/ noun, plural nine·ti·eths [count]
▪ one ninetieth of the total cost
/ˈnaɪntijəθ/ noun, plural nine·ti·eths [count] ▪ one ninetieth of the total cost
— ninetieth adjective
▪ her ninetieth birthday
▪ her ninetieth birthday
— ninety adjective
▪ ninety dollars
▪ ninety dollars
— ninety pronoun
▪ We spent thirty dollars and had ninety left.
▪ We spent thirty dollars and had ninety left.
