The phrase "tightly-packed" is often used to describe a space or object that has been filled or compressed in a dense manner. There are several other synonyms for this phrase that can be used in place of "tightly-packed." These synonyms include "crowded," "cramped," "compressed," "condensed," "intense," "solid," and "packed." These words all suggest a sense of density and compression, and can be used interchangeably with "tightly-packed" in most contexts. However, it is important to note that each of these synonyms has a slightly different shade of meaning, so it is important to choose the right one based on the precise nature of the thing being described.