Breadcrumb Home > Thesaurus > U Synonyms of unsubstantial Find synonyms for: Adjective 1. insubstantial (vs. substantial), unsubstantial, unreal, aeriform, aerial, airy, aery, ethereal, shadowy, wraithlike, stringy, immaterial#3, nonmaterial usage: lacking material form or substance; unreal; "as insubstantial as a dream"; "an insubstantial mirage on the horizon" WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of unsubstantial (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: antecedent Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language