/ Thesaurus / D Synonyms of debt instrument Find synonyms for: Noun1. debt instrument, obligation, certificate of indebtedness, documentusage: a written promise to repay a debtWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: heifer Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language