Dumbfound (11)
'dumbfound' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for flabbergast that I've seen before include "Strike dumb" , "Astonish" , "floor" , "Astound" , "stunning" .)
'dumbfound' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for stun that I've seen before include "Knock unconscious" , "deliver a knock-out blow" , "Concuss; amaze" , "Stagger, amaze" , "Amaze; knock senseless" .)
'dumbfound' is the definition.
(I know that dumbfound can be written as nonplus)
This is all the clue.
(Other definitions for nonplus that I've seen before include "Flummox" , "Baffle" , "'Disconcert, puzzle (7)'" , "Perplex completely with negative and positive" , "Perplex, confound" .)