slechtst

worst(adjective)

bad to the greatest extent

That is the worst book I have ever read.

het minst goed

worst(adverb)

in the worst way or manner

This group performed worst (of all) in the test.

de/het ergste, slechtste

worst(pronoun)

the thing, person etc which is bad to the greatest extent

the worst of the three; His behaviour is at its worst when he's with strangers; At the worst they can only fine you.