speechless
US /ˈspiːtʃ.ləs/
UK /ˈspiːtʃ.ləs/

1.
sprachlos, stumm
unable to speak, especially as a result of shock or strong emotion
:
•
She was left completely speechless by the unexpected proposal.
Sie war völlig sprachlos von dem unerwarteten Antrag.
•
He was speechless with rage.
Er war sprachlos vor Wut.