/ Thesaurus / R Synonyms of regretfully Find synonyms for: Adverb1. regretfullyusage: with regret (used in polite formulas); "I must regretfully decline your kind invitation"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language