/ Thesaurus / C Synonyms of costus oil Find synonyms for: Noun1. costus oil, essential oil, volatile oilusage: a yellow volatile essential oil obtained from costusroot; used in perfumesWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: devout Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language