/ Thesaurus / B Synonyms of black catechu Find synonyms for: Noun1. black catechu, catechu, infusion, extractusage: extract of the heartwood of Acacia catechu used for dyeing and tanning and preserving fishnets and sails; formerly used medicinallyWordNet 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