/ Thesaurus / S Synonyms of september 11 Find synonyms for: Noun1. 9/11, 9-11, September 11, Sept. 11, Sep 11usage: the day in 2001 when Arab suicide bombers hijacked United States airliners and used them as bombsWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: nefarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language