-는 사이에
Used when something happens in the brief interval or gap between two moments/events. Often implies something happened unexpectedly fast.
Summary
Equivalent
While / In the time it takes / In the brief moment that
Also: -는 동안에 (While/during — extended period; '-는 사이에' is a brief gap or interval)
Example
While I stepped away briefly, the documents disappeared.
잠깐 자리를 비운 사이에 서류가 없어졌어요.
Grammar rules
- '사이' means 'interval' or 'gap'.
- '-는 사이에' captures a short window: '잠깐 자리를 비운 사이에 지갑이 없어졌어요' (While I stepped away briefly, my wallet disappeared).
Patterns
Verbs (Intervening Moment)
Present/Past · Verb Stem + 는 사이에
Example sentences
While I stepped away briefly, the documents disappeared.
잠깐 자리를 비운 사이에 서류가 없어졌어요.
In the blink of an eye, the child has grown up.
눈 깜짝할 사이에 아이가 컸네요.
While I went to the bathroom, my friend showed up.
제가 화장실에 간 사이에 친구가 와 버렸어요.
Conversation
A: Did you miss the bus?
버스를 놓쳤어요?
B: Yes, while I was briefly looking for my bag the bus came and just left.
네, 잠깐 가방을 찾는 사이에 버스가 와서 그냥 가 버렸어요.
Practice
Fill in the blank
Express what happened in a brief interval.
Phone call.
Looking down.