/ Thesaurus / S Synonyms of startle reaction Find synonyms for: Noun1. startle response, startle reaction, startle, jump, startusage: a complicated involuntary reaction to a sudden unexpected stimulus (especially a loud noise); involves flexion of most skeletal muscles and a variety of visceral reactionsWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: eccentric Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language