sunk

Sunk is the past participle of the verb sink and an adjective describing something that has been submerged or is below the surface. It is used for objects that have descended beneath a liquid boundary or otherwise disappeared from view. In grammar, sunk is used with auxiliary verbs to form perfect tenses: for example, a ship has sunk.

Common forms include sank (the simple past) and sunk (the past participle). The phrase "the ship sank" uses sank, whereas "the ship has sunk" uses sunk.

Sunk costs: In economics and decision theory, a sunk cost is a cost that has already been incurred and cannot be recovered. The sunk cost fallacy describes the tendency to factor such costs into future decisions, leading to suboptimal choices.

Usage notes: Both sunken and sunk can describe something below the surface; sunken is often preferred when referring to physical features or objects that are now beneath the surface, whereas sunk is common in fixed phrases such as sunk ship or sunk cost. The term appears in archaeology, marine science, and literature to denote underwater state.