Caved-in refers to a situation where a structure or surface collapses or caves inwards. Some synonyms for caved-in include collapsed, crumbled, and gave way. Other alternatives for the word include tumbled, fallen, or slumped. The term can also be described as "imploded" or "sunk", indicating that the structure or surface has collapsed under pressure. In some cases, caved-in can be substituted with the phrase "sunken-in", which refers to a space that has sunk or collapsed inwardly. These synonyms can be used to describe the state of buildings, tunnels, and natural formations that have been impacted by wear and tear or external forces.