/ Thesaurus / G Synonyms of genus costia Find synonyms for: Noun1. genus Costia, protoctist genususage: a genus of flagellate protoctistWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: endear Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language