Unimproved is a term used to describe something that is in its raw or natural state and has not undergone any enhancement or development. Its antonyms include words such as "enhanced," "improved," "refined," "polished," "advanced," and "progressed." These words signify the opposite of unimproved, suggesting that something has been altered in a positive manner, made better, or progressed in some way. Improving something could mean to add more features, increase its performance, or refine its quality. It could also mean to make it more adaptable and suitable for the given use. Thus, identifying the antonyms of unimproved can help to give insight into how something could be improved.