Well English isn't Japanese. the word "marui" is an -i word, which is is a type of word that doesn't exist in English: an adjective with tense (or a stative verb?) English adjectives can often also be nouns, so the adjective "round" is also a noun "round", with related meaning. The word is also a verb. Then again the senses of marui are no all shared by "round", in particular the sense of "gentle person".

in both languages.

Last question: Can I rest assured that "Slice a carrot into rounds" sounds perfectly natural?