Ringforts, known in Irish as raths, were the enclosed farmsteads of early medieval Ireland, typically dating from around the fifth to the twelfth centuries. They consisted of one or more earthen banks surrounding a domestic interior, and the presence or absence of an entrance tells archaeologists a great deal about how a site was used and how well it has survived. At Cloonadrum, that entrance simply cannot be identified, which sets this particular example slightly apart from the broader pattern.

The monument sits on the gentle southern slope of an east-west ridge and takes a subcircular form, measuring roughly 26 metres across east to west and 24 metres north to south across its interior. It follows the classic rath arrangement: an inner earthen bank separated by a fosse, the ditch that runs around the outside of the bank, from a second outer bank beyond. The fosse here has a base width of between one and a half and three metres, and drops to about a metre at its deepest. The outer bank is wider than the inner, ranging from five and a half to eight metres across, though it stands only a few centimetres above the surrounding ground. A later field boundary has been built directly over the outer bank on the north-northwest side, which is a common fate for monuments that continued to shape the landscape long after their original purpose was forgotten. The outer bank is also damaged and the fosse filled in at the east-northeast over a stretch of about eight and a half metres, which may be where an entrance once existed, though no firm trace remains. Two shallow hollows inside and just outside the enclosure add further texture without yet yielding an explanation; they may be the remnants of pits, collapsed features, or simply the uneven settling of old ground.