Rathbaun, in Irish something close to "the yellow rath", contains within it the word for the very thing that survives in the field: a rath, the Hiberno-English term for a ringfort, those circular enclosures of earthen bank and ditch that were once the farmsteads and defended homesteads of early medieval Ireland. That the townland is named after such a structure suggests the monument was conspicuous enough, and prominent enough in local life, to give its character to the surrounding land. Ringforts are among the most numerous archaeological monuments in the Irish countryside, with estimates running to tens of thousands across the island, yet each one represents an individual household or small community, most likely dating to somewhere between the fifth and twelfth centuries.

A rath, in its simplest form, consists of one or more circular earthen banks enclosing a roughly level interior, with a ditch cut outside the bank and a single entrance causeway. The interior would have held a dwelling house and outbuildings; the enclosure itself was less a military fortification than a boundary marker, a statement of ownership and status, and a means of controlling livestock. In parts of Connacht, including County Mayo, these monuments are woven into the agricultural landscape at considerable density, many surviving as low, grassed-over rings in pasture fields, their profiles worn down by centuries of ploughing and grazing. The name Rathbaun suggests this particular example may have been distinguished at some point by its appearance, perhaps the colour of its exposed subsoil or the quality of its surviving earthworks, though the precise character of the monument at this location is not fully documented in publicly available sources at present.