/ Thesaurus / S Synonyms of sidesplittingly Find synonyms for: Adverb1. killingly, sidesplittinglyusage: in a very humorous mannerWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: morose Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language