be lost for words
US /bi lɔst fɔr wɜrdz/
UK /bi lɔst fɔr wɜrdz/

1.
ficar sem palavras, perder a fala
to be so surprised, confused, or emotional that you cannot think of anything to say
:
•
When she saw the surprise party, she was completely lost for words.
Quando ela viu a festa surpresa, ficou completamente sem palavras.
•
His rude comment left me lost for words.
O comentário rude dele me deixou sem palavras.