Breadcrumb Home > Thesaurus > S Synonyms of seismic Find synonyms for: Adjective 1. seismic, seismal, unstable (vs. stable) usage: subject to or caused by an earthquake or earth vibration WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of seismic (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: agitprop Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language