The constructed language Lojban doesn't actually differentiate between adjectives, verbs, nouns and adverbs, because it turns out separating words into categories like that isn't a useful exercise.

For example, is "shower" a noun or a verb? What about "bike?"

Take the word "green." In English, color words are pretty strictly adjectives. in English, you say a traffic light "turns green." In Lojban, you would say the light "is greening" or "greens." Funny how you can also make English do that, huh?