Measuring just sixty centimetres tall and roughly thirty-two centimetres at its base, the cross-slab at Rosmore is irregular in outline, as though shaped with more intention than precision. Cut into its face is a deeply incised Greek cross, the kind with four arms of equal length, each terminal widening into a distinctive T-shape. That detail, the splayed horizontal cap at the end of each arm, sets it apart from the more common plain incised crosses found elsewhere on early slabs.

Cross-slabs of this type belong broadly to the early medieval period of Irish Christianity, when carved stones served as grave markers or devotional objects within monastic and ecclesiastical enclosures. The Greek cross form, as distinct from the Latin cross with its elongated lower arm, appears frequently in early Irish Christian stonework, and the T-shaped terminals seen here are a recognised variant that adds a degree of formality to what is otherwise a modest piece. The slab sits in the northern half of the burial ground at Rosmore, a placement that may reflect older patterns of use within the site, as certain areas of early graveyards were sometimes reserved for particular purposes or periods of use.