The "moyle" element, appearing in place names across Ireland, is generally understood to derive from the Irish "maol", meaning a bare or rounded hill, and the "castle" prefix suggests that whatever structure gave this townland its identity was substantial enough to leave a lasting impression on the local geography, even if the building itself has long since faded from ready description.

The house takes its name from the townland of Castlemoyle, and that layering, a later residential building inheriting the identity of an earlier fortified one, is a pattern found throughout Connacht, where successive centuries of settlement often compressed themselves onto the same patch of ground. Country houses in this part of Galway frequently rose on or near the sites of tower houses or bawn enclosures, the latter being walled courtyards that once offered protection to livestock and inhabitants alike. Whether Castlemoyle follows that pattern precisely is not currently documented in publicly available records, which places it in an intriguing category: a named, mapped, and formally recognised site whose particular history remains largely unwritten in accessible form.