The designation itself raises questions. Religious houses in Ireland range from early medieval monastic enclosures to later medieval friaries and nunneries, and the term can cover anything from a modest hermitage to a substantial conventual complex. That ambiguity, combined with the near-total absence of publicly available detail, gives Derreen an unusual quality among listed monuments: it is known to exist as a classified site, but almost nothing about its form, date, or history has filtered through to general circulation.

Derreen as a place-name derives from the Irish word for a small oak wood, a common topographical description found across many Irish counties. Galway has a long and layered history of religious settlement, from the early Christian period through the monastic reforms of the twelfth century and into the Hiberno-Norman era, when new religious orders established houses across Connacht. Without further detail on record, it is not possible to say which tradition or period this particular site belongs to, or what physical traces, if any, remain above ground.