This is the 12763rd most frequent Korean word.
더러
"더러" means "to some people" or "to someone" in Korean.
In this context, '더러' implies 'to' or 'toward someone' as the indirect object of the action.
그는 나에게 더러 공부하라고 말했다.
He told me to study.
Here, '더러' is part of the word '더럽다', which means 'dirty'.
그 방은 너무 더러워서 청소가 필요해요.
That room is so dirty that it needs cleaning.
Usage of '더러움' (noun form of 더럽다) to denote 'dirtiness'.