The term "unbuilt" typically refers to something that has not been constructed or developed. Some antonyms for this word could be built, developed, constructed, established, completed, or finished. These antonyms imply that the thing referred to has gone through some kind of process or evolution and is now a tangible entity. For example, a construction site that was previously "unbuilt" could become "built" once it has been developed into a completed building. Similarly, a project that was once "unbuilt" could become "established" or "completed" once it is finished. These antonyms help to convey the progression and growth of a project, making them useful for writers who wish to express change and development.