How do you...

Form a negative comparative/superlative with an adjective…

i.e. less pretty/least pretty = ?/?
as opposed to
prettier/prettiest = pulchrior/pulcherrima

minus pulcher (pulchra, pulchrum) minime pulcher (pulchra, pulchrum)

Ah, I see. So you put the adverbial form of parvum in a comparative/superlative degree along with the adjective?