värsta

Etymology 1
Superlative attributive of, the superlative predicative is. The positive has a suppletive inflection.

Etymology 2
From the superlative form above where the meaning most bad or most poor has gotten an opposite meaning. A similar analogy can be seen in which originally means "cruel" but has gotten a meaning of "awesome" or "cool" instead. Interestingly enough the same has happened with cruel in English which also can mean "awesome" or "cool", colloquially.

Adjective

 * 1)  An intensifier.

Usage notes
"Someone/something /verb/ värsta /noun in the definite form/" is the way that phrases are constructed using this word.