From Old Norse verri (“worse”). A comparative form, from Proto-Germanic *wirsizô.
værre (comparative, superlative (predicative) værst, superlative (attributive) værste)
- bad, difficult, disadvantageous, serious, troublesome, unlucky, unpleasant
This is a comparative form missing a positive form, hence it can be interpreted as the suppletive comparative form of dårlig and slem, respectively.
værre (comparative, superlative værst)
- worse, more bad, more badly