The word "kill" derives from the Irish "cill", meaning a church or monastic cell, and its appearance here points to an early ecclesiastical origin, even though no church building survives above ground. What remains is the enclosure itself: roughly 34.5 metres long and 28.5 metres wide, its perimeter wall standing about 1.2 metres high and nearly 1.7 metres thick, with a gap of around six metres opening to the west-northwest.

Burial grounds of this type, sometimes called "cilliní" when associated with unconsecrated use, or simply early Christian enclosures when linked to a vanished church, are scattered across the Irish countryside, often outlasting by many centuries the structures they once surrounded. The substantial width of the wall at Aultaghreagh suggests it was built to last and likely to keep grazing animals out rather than for any defensive purpose. Some grave markers are still present within the enclosure, though the site sits quietly in ordinary farmland with no obvious monument to draw the eye. The 1842 OS six-inch map, one of the most detailed surveys of pre-Famine Ireland, caught it at a moment when local memory of its function was evidently still intact enough to name it clearly.