A souterrain is a man-made subterranean structure, typically stone-lined, built during the early medieval period in Ireland as a place of refuge, storage, or concealment. They are found across the country in their hundreds, often associated with ringforts or early ecclesiastical settlements, and the one at Cashel belongs to this quiet, largely invisible category of monument that rewards the curious but rarely announces itself.

Beyond the classification and location, the specific details of this particular souterrain remain sparse. The townland name, Cashel, is itself suggestive. A cashel is a type of stone-walled enclosure, the western Irish equivalent of the more familiar earthen ringfort, and the presence of such a place-name often points to a cluster of early medieval activity in the surrounding landscape. Whether this souterrain is directly associated with a cashel enclosure, or simply shares a name with the townland it happens to occupy, is not currently documented in available sources.