- ninety, 90, XC - the cardinal number that is the product of ten and nine
--1 is a kind of decade, decennary, decennium; large integer; decade, decennary, decennium; large integer
- nineties, 1990s - the decade from 1990 to 1999
--2 is a kind of decade, decennary, decennium; decade, decennary, decennium
- nineties, mid-nineties - the time of life between 90 and 100
--3 is a kind of time of life; time of life
--3 is a part of old age, years, age, eld, geezerhood