"Heavily populated" means an area that has a high density of inhabitants or a large number of people living in a particular place. Instead of using this phrase repeatedly, there are numerous synonyms that can be used for it, such as densely populated, crowded, jam-packed, bustling, teeming, swarming, overrun, brimming, lousy, infested, and thriving. These words convey similar meanings to "heavily populated" and help to avoid repetition in written or spoken language. Choosing the right synonym will also depend on the context and the intended tone of the message. For instance, "crowded" or "jam-packed" can have a negative connotation, while "thriving" implies growth and prosperity.