The one on low ground outside Fedamore in County Limerick breaks that pattern entirely. It is trapezium-shaped, a geometry so unusual in this context that the archaeologist who recorded it in 1942 to 1943 felt the need to explain every angle in careful detail: right angles at the two northern corners, an obtuse angle where the southern side meets the western, and four sides of notably different lengths. A fosse, which is a dug ditch used as a boundary or defensive feature, runs around the interior, with a bank raised from the excavated earth on its inner edge. Only a causeway crossing the fosse on the north side marks where an entrance once stood; the bank along that same side has since disappeared.

The survey record comes from O'Kelly, writing in 1942 to 1943, who measured the enclosure at 119 metres along the west side, 64 metres along the north, 69 metres along the east, and 76 metres along the south. Even at those dimensions, the monument resists easy classification. O'Kelly noted that the surrounding field was divided by old fences of uncertain age, and that the bank and fosse were already overgrown and sitting on poor, low-lying ground. More recent aerial photography from Digital Globe has revealed cropmarks of the enclosure alongside ridge and furrow cultivation ridges nearby, the kind of corrugated earthwork left by repeated ploughing across the same strips of land over many seasons. Whether the enclosure was once the central paddock or large field of a small agricultural complex is unresolved. Fedamore Church lies roughly 220 metres to the south, and the site of Fedamore Castle around 500 metres to the south-west, suggesting this corner of the parish has seen long, layered use.

The enclosure sits on low farmland and is not formally presented as a visitor site; the bank and fosse remain overgrown, as they were when O'Kelly visited. The clearest view of its unusual shape is actually from above, visible in aerial imagery rather than from the ground. Anyone walking the area should look for the slight rise of the surviving bank and the depression of the fosse, particularly along the west and south sides where they are best preserved. The proximity of the church and castle site means the wider landscape rewards a slow, attentive approach on foot.