This is the 6378th most frequent Korean word.
앉아있던
"앉아있던" means "was sitting" in English.
앉아있던 is used as a descriptor for the man, indicating he was in a seated position at the moment being referred to.
그녀는 공원 벤치에 앉아있던 남자와 이야기를 나누었다.
She talked with the man who was sitting on the park bench.
앉아있던 characterizes the cat in a seated state before its sudden action.
앉아있던 고양이가 갑자기 뛰어올랐다.
The cat that was sitting suddenly jumped up.
앉아있던 specifies the state preceding the observation about the seat.