/ Thesaurus / F Synonyms of frightfully Find synonyms for: Adverb1. terribly, awfully, awful, frightfullyusage: used as intensifiers; "terribly interesting"; "I'm awful sorry"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: dormant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language