The antonyms for the word "un-populated" are "densely populated", "crowded", "peopled", "thickly settled", "inhabited", and "populous". These words refer to areas that are heavily populated with large numbers of people residing in a specific region. Such areas are characterized by bustling streets, high-rise buildings, and a significant amount of social and economic activities. Unlike un-populated areas, densely populated regions present various challenges such as inadequate housing, traffic congestion, and high levels of pollution. However, they may also present numerous opportunities for business and cultural activities. Therefore, the antonyms for un-populated reflect a society that is well-developed and flourishing.