Can someone explain/clarify the masculine and feminine forms of orange in Italian? The vocab section suggests that there are only two forms, "arancionI" and "arancione".
What about brown? Is it only "marrone"?
These are both examples of what are called "invariable" adjectives. There is no masculine or feminine form, only forms for singular and plural. Colors in particular can have some very strange forms in Italian (for example, "blu" has a single form for every use).