A souterrain is an artificially constructed underground passage or chamber, typically built from stone, and usually associated with early medieval settlement. They are found across Ireland in considerable numbers, yet their precise function remains a matter of ongoing discussion among archaeologists. Likely uses include food storage, taking advantage of the consistently cool underground temperature, refuge during periods of raiding, or simple secure storage for valuables. The Graffy example is recorded as a monument in its own right, which points to its survival in some recognisable form, though the details of its construction, dimensions, and condition remain to be fully set out in the public record.

Souterrains in the west of Ireland are often found in association with ringforts or early ecclesiastical sites, and County Mayo has a reasonable concentration of them scattered across its townlands. They were typically constructed during the early medieval period, roughly between the seventh and twelfth centuries, though the specific dating of any individual example depends on excavation evidence or associated finds. The name Graffy itself is an anglicisation of an Irish place name, as is common throughout Mayo, and such names frequently encode older references to landscape features, families, or land use that have otherwise vanished from living memory. Without further documented detail specific to this site, the broader context of Mayo souterrains serves as the nearest available frame of reference.