/ Thesaurus / O Synonyms of osteostraci Find synonyms for: Noun1. Osteostraci, suborder Osteostraci, Cephalaspida, suborder Cephalaspida, animal orderusage: extinct group of armored fish-like vertebrates; taxonomy is not clearWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language