/ Thesaurus / P Synonyms of plus sign Find synonyms for: Noun1. plus sign, signusage: a sign indicating the operation of additionWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: diaphanous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language