(ο) χειρότερος

worst(adjective)

bad to the greatest extent

That is the worst book I have ever read.

χειρότερα

worst(adverb)

in the worst way or manner

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

(ο) χειρότερος, (η) χειρότερη περίπτωση

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.