Sun-tanned is a common term used to describe skin that has been darkened due to the sun's exposure. However, there are many synonyms for this term that can add variety to your writing. Some examples include bronzed, tawny, toasted, burnt, golden-brown, caramelized, sun-kissed, and coppery. The use of different synonyms can evoke different imagery and moods. Bronzed and coppery can imply a richer and more luxurious tone, while toasted and burnt can have negative connotations. It is important to choose the right synonym that will enhance the context and tone of your writing.