"Un-adorned"; a word that describes something that is plain and simple without any decorative embellishments. Antonyms to this word could include "adorned"; something that is embellished, decorated or ornamented with beautiful accents. Another antonym could be "ornate"; something that is highly decorated, complex and intricate. "Elaborate" could also serve as an antonym, meaning something that is detailed, complex and refined in its design. "Fancy" could serve as well, highlighting something that is ornate and showy, with attention paid to the smallest detail. Other antonyms could include "decorated", "ornamented", "embellished", and "flamboyant".