The structure measures roughly 22 metres north to south and nearly 25 metres east to west, dimensions that place it comfortably within the range of early historic or prehistoric enclosures found across Munster. On its western side, some stones are set radially into the wall, a detail that breaks the otherwise uniform character of the boundary and hints at deliberate construction choices that no longer have an obvious explanation.

Enclosures of this kind, roughly circular areas defined by an earthen or stone bank, are among the more common yet least understood monument types in the Irish landscape. They may have served as farmsteads, stock enclosures, ceremonial spaces, or burial grounds depending on their period and context, and without excavation it is rarely possible to say which. At Derryishal, the picture is further complicated by the fact that the northern half of the interior now lies under forestry, obscuring whatever surface features might once have offered further clues. The modern stone wall capping the original bank is a familiar sight on sites like this across Ireland, where farmers over the centuries have found ready-made boundaries worth reusing rather than building from scratch.