The site is listed as a souterrain, the term used in Irish archaeology for an underground passage or chamber, typically stone-built and associated with early medieval settlements, used variously for refuge, storage, or both. What makes Ballinvoher quietly odd is the qualification attached to it: the cave may not be a souterrain at all, but a natural limestone feature, the kind of hollow that forms when water slowly dissolves the bedrock beneath the Connacht plain.

The distinction matters, because it places the site somewhere between human history and geology. Much of north Galway sits on karst limestone, a landscape riddled with natural cavities, sinks, and underground drainage. A community encountering such a feature might have adapted it for use, or simply noted it as something remarkable, and the memory of its existence would then travel forward through generations as local tradition, gradually acquiring the word "cave" without any particular agreement about what made it so. The blocked entrance means that question may remain open.