This is the 71st most frequent Korean word.
않은
"Not" or "did not" (used to negate verbs).
Here, '않은' modifies '상태로' to indicate a state of continuous action without resting.
나는 쉬지 않은 상태로 이 일을 끝냈다.
I finished this work without resting.
In this sentence, '않은' describes '모습' to express a state of not enduring.
그는 하나도 참지 않은 모습을 보였다.
He showed a state of not having held back at all.
'않은' modifies '공간' to describe a space that has not experienced the action of being opened.