/ Thesaurus / B Synonyms of back number Find synonyms for: Noun1. has-been, back-number, oldster, old person, senior citizen, golden agerusage: someone who is no longer popularWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language