/ Thesaurus / S Synonyms of sea slug Find synonyms for: Noun1. sea slug, nudibranch, gastropod, univalveusage: any of various marine gastropods of the suborder Nudibranchia having a shell-less and often beautifully colored bodyWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: eccentric Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language