Breadcrumb Home > Thesaurus > O Synonyms of optional Find synonyms for: Adjective 1. optional (vs. obligatory), elective, ex gratia, facultative, nonmandatory, nonobligatory usage: possible but not necessary; left to personal choice WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of optional (Dictionary) TrendingHere are the facts and trivia that people are buzzing about. Hanukkah Origins of the Christmas Holiday Jewish Holidays, 2010-2030 (A.M. 5770-5791) Western Christian Holidays, 2010-2030 Krampus: The Christmas Devil Kwanzaa ✖ Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language