The word "sinkable" means capable of sinking or being sunk. Some potential synonyms for "sinkable" include words such as "submersible," "immersive," "go-downable," and "plunge-worthy." "Submersible" is often used to describe boats or submarines that are designed to operate underwater. "Immersive" can be used to describe an experience that feels like being submerged, such as a virtual reality game. "Go-downable" is a more colloquial term that implies something can be easily submerged or sunk. "Plunge-worthy" is a more subjective term that implies something is worth sinking or submerging.