There are several synonyms one can use for the term "dense masses". The phrase can be replaced by "concentrated clumps", "compact heaps", "thick clusters", or "solid conglomerations". Another way to express this term is to say "tightly packed masses" or "compressed formations". These synonyms accurately describe a mass of objects or substance that is closely packed together with very little space in between. The term can be applied to a variety of scenarios, such as a cluster of trees or a group of people in a crowded room. The use of synonyms helps to add variety and interest to written content.