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

1.
말문이 막히다, 할 말을 잃다
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.
그녀는 깜짝 파티를 보고 완전히 말문이 막혔다.
•
His rude comment left me lost for words.
그의 무례한 말에 나는 말문이 막혔다.