/ əˈstaʊnd; NAmE / verb
[ vn ] to surprise or shock sb very much
SYN astonish :
His arrogance astounded her.
She was astounded by his arrogance.
➡ note at surprise
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WORD ORIGIN
Middle English (as an adjective in the sense stunned ): from astoned , past participle of obsolete astone stun, stupefy , from Old French estoner , based on Latin ex- out + tonare to thunder.