These grounds are known in Irish as cillíní, singular cillín, and they served as burial places for those who, under Catholic tradition, were excluded from consecrated ground. Most commonly, this meant unbaptised infants, though stillborn children, and in some periods individuals who had died by suicide or outside the sacraments, were also interred in such places. The cillín was typically a liminal space, neither fully sacred nor entirely secular, often sited at the edge of a parish, near an ancient monument, or at a boundary of some kind.

The name Dumha Éige itself is worth pausing on. Dumha is an Irish word for a mound or burial mound, suggesting the site may be associated with, or located near, an earlier earthwork of some antiquity. This kind of layering is not unusual with cillíní; early Christian and prehistoric sites were sometimes chosen deliberately for children's burials, perhaps because they carried their own older sense of sanctity or otherworldliness. The practice of burying unbaptised children in cillíní persisted in parts of rural Ireland well into the twentieth century, though it has declined significantly since then. Many such sites remain unmarked and are identified only through local memory or occasional archaeological survey.