Un-prosperous, meaning not successful or not flourishing, is an antonym of prosperous. The antonyms of un-prosperous can be various words that represent success and growth, such as prosperous, thriving, blooming, booming, flourishing, successful, and affluent. Prosperous means having success or good fortune, while thriving implies growth and progress. Booming suggests rapid growth or expansion, and blooming refers to a process of blossoming or blooming. Flourishing means growing and prospering, and successful means achieving desired goals or objectives. Finally, affluent refers to the state of possessing great wealth and financial prosperity. These antonyms convey a sense of thriving and success, standing in contrast to the notion of un-prosperous.