This is the 19016th most frequent Korean word.
아닌지
"아닌지" means "whether or not it is not."
In this sentence, '아닌지' is used to express uncertainty about whether something might not be true.
그것이 사실이 아닌지 확인해야 합니다.
We need to verify if that is not true.
Here, '아닌지' reflects a questioning or speculative stance on whether something does not meet the desired criteria.
이것이 우리가 찾던 것이 아닌지 고민해 봅시다.
Let's think about whether this is not what we were looking for.
'아닌지' in this case conveys curiosity about whether the subject doesn't match certain characteristics