This is the 19296th most frequent Korean word.
않았거나
"Did not or have not."
않았거나 is used as a logical operator indicating an alternative between two negative actions.
그는 학교에 가지 않았거나 숙제를 하지 않았을 것입니다.
He must have either not gone to school or not done his homework.
않았거나 connects two negative verbs to offer alternate conditions.
비가 오지 않았거나 바람이 불지 않았을 때 나갔어요.
I went out when it either was not raining or it was not windy.
않았거나 provides a choice between two actions that did not occur.