/ Thesaurus / 9 Synonyms of 90 Find synonyms for: Noun1. ninety, 90, XC, large integerusage: the cardinal number that is the product of ten and nineAdjective1. ninety, 90, xc, cardinal (vs. ordinal)usage: being ten more than eightyWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: confectionery Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language