dumbfounded
adj. B2 Upper Intermediate US //ˈdəmfaʊndɪd// UK //dˈʌmfaʊndɪd// dumb·found·ed
adj. so shocked or surprised that you cannot speak for a moment.
adj. temporarily unable to speak due to extreme astonishment or disbelief. Often used predicatively after linking verbs like 'be', 'look', or 'stand'.
She stood there dumbfounded after hearing the news.
The audience was left dumbfounded when the magician made the entire grand piano disappear from the stage.
The investigators were utterly dumbfounded by the lack of physical evidence at the scene, as it contradicted every witness testimony they had gathered so far.
Usage
Typically follows a linking verb such as 'be', 'remain', or 'stand'.