-던데(요)

I noticed that … (recalling my own experience, inviting a reaction)

Level 4 · TOPIK II · intermediate

How to use it

The speaker recalls something they directly experienced. As a sentence ending (-던데요) it leaves room for the listener's reaction and often sounds mildly surprised or softly contrary. Mid-sentence (-던데) it gives background before a question, suggestion, etc.

Forming it

맛있다	→ 맛있던데요
바쁘다	→ 바쁘던데요
학생	→ 학생이던데요
가수	→ 가수던데요

Only for what you actually saw or experienced, not for facts you merely heard. About yourself, it's used only for feelings or sensations, not your own actions (✗ 제가 어제 학교에 가던데요).

Examples

그 식당 음식이 정말 맛있던데요.
The food at that restaurant was really good (I found).
어제 보니까 동생이 많이 바쁘던데 무슨 일 있어요?
I saw yesterday that your sibling was really busy. Is something going on?

Compared with similar patterns

-더라고요 (G3-007) simply reports a recollection; -던데요 leaves it open and often implies contrast or expects a response. -더군요 (G4-004) is a recollected realization. -(으)ㄴ/는데요 (G2-025) is the same soft ending without the 'I experienced it' meaning.