The term "un-aesthetic" refers to something that is visually displeasing, unattractive or lacking beauty. Therefore, the antonyms for this term would include words such as "beautiful", "gorgeous", "pleasing", "appealing", "attractive", "charming", "lovely", "stunning", "handsome", "striking", "exquisite", "elegant", "graceful", and "picturesque". All of these words describe things that are pleasing to the eye, attractive and visually appealing. So, if you want to describe something that is beautiful and eye-catching, you can use one of these antonyms for the word "un-aesthetic".