Word Study
flabbergast
OXFORD DICTIONARY
flabbergast, v.tr. (esp. as flabbergasted adj.) colloq. overwhelm with astonishment; dumbfound.
Etymology
18th c.: perh. f. FLABBY + AGHAST
THESAURUS
flabbergast
amaze, astonish, astound, awe, awestrike, bedaze, bedazzle, bewilder, boggle, bowl down, bowl over, confound, daze, dazzle, dumbfound, dumbfounder, overwhelm, paralyze, perplex, petrify, shock, stagger, startle, strike dead, strike dumb, strike with wonder, stun, stupefy, surpriseROGET THESAURUS
flabbergast
Wonder
VB wonder, marvel, admire, be surprised, start, stare, open one's eyes, rub one's eyes, turn up one's eyes, gloar, gape, open one's mouth, hold one's breath, look aghast, stand aghast, stand agog, look blank, tombe des nues, not believe one's eyes, not believe one's ears, not believe one's senses, not be able to account for, not know whether one stands on one's head or one's, surprise, astonish, amaze, astound, dumfound, dumfounder, startle, dazzle, daze, strike, strike with wonder, strike with awe, electrify, stun, stupefy, petrify, confound, bewilder, flabbergast, stagger, throw on one's beam ends, fascinate, turn the head, take away one's breath, strike dumb, make one's hair stand on end, make one's tongue cleave to the roof of one's mout, make one stare, take by surprise, be wonderful, beggar description, beggar the imagination, baffle description, stagger belief.For further exploring for "flabbergast" in Webster Dictionary Online