Derived from the Irish eaglais, meaning church, it is one of those place-names scattered across Ireland that records the presence of an early ecclesiastical site long after the physical remains have blurred into the landscape. A townland named for a church usually means the building, or its predecessor, came first, and the surrounding identity grew around it.

The church at Aglish in County Kilkenny sits within this tradition of early Irish ecclesiastical settlement, where small communities gathered around a founder's oratory or monastic enclosure, often pre-dating the arrival of the Anglo-Norman parish system that reorganised much of rural Ireland from the twelfth century onward. Kilkenny as a county contains a dense concentration of such sites, many of them associated with the early medieval church before diocesan structures formalised boundaries and consolidated worship into larger, more permanent stone buildings. The name alone suggests the site has considerable age behind it, even where the standing fabric may reflect later rebuilding or has largely disappeared.