-(이)라고요? / -다고요? (reprise)
ask for repetition or echo what was said
Form
In 뭐라고요?, 뭐 + 라고요? forms a polite echo question: “what did you say? / pardon?” More generally, -(이)라고요? echoes a quoted noun and -다고요? echoes a quoted clause.
Function
Asks for repetition or echoes what was just heard, often with surprise or disbelief. The focus is the previous utterance, not the identity of an object.
Why this form?
뭐예요? — “what is it?”: asks for the identity or nature of a thing; 뭐라고요? asks what was said.
뭐라고 했어요? — “what did you say?”: a full, explicit question; 뭐라고요? is a shorter spoken reaction that is natural immediately after surprising words.
네? — “pardon?”: a plain request for repetition; 뭐라고요? can convey stronger surprise at the content heard.
Register and nuance
뭐라고요? is common in polite speech. Without 요, 뭐라고? is casual.
Forms not to confuse
뭐예요?
저게 뭐예요? — What is that?
뭐라고 했어요?
방금 뭐라고 했어요? — What did you just say?
네?
네? 잘 못 들었어요. — Pardon? I didn’t hear you well.
Examples
뭐라고요? 태형 씨도요? — Pardon? You too, Taehyung?
다음 주라고요? — You said next week?