Breadcrumb Home > Thesaurus > U Synonyms of unfasten Find synonyms for: Verb 1. unfasten, undo usage: cause to become undone; "unfasten your belt" 2. unfasten, open, open up usage: become undone or untied; "The shoelaces unfastened" WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of unfasten (Dictionary) TrendingHere are the facts and trivia that people are buzzing about. Jewish Holidays, 2010-2030 (A.M. 5770-5791) Western Christian Holidays, 2010-2030 12 Steps to a New Year New Year's Resolution to Slim Down? Martin Luther King Speeches Books of the Bible: Old Testament Books in Order ✖ Related Content Daily Word Quiz: voxpopuli Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language