The element "kill" derives from the Irish "cill", meaning a church or monastic cell, and its presence in a townland name almost always signals an early ecclesiastical site somewhere nearby, often predating the Norman arrival and sometimes stretching back to the earliest centuries of Irish Christianity. The church at Kilgreana in County Mayo is one such site, a monument whose name alone suggests considerable age, even where documentary detail remains thin.

The townland name points to a founding figure or patron whose identity has not been firmly established in surviving records, a common situation with early Irish church sites, many of which were associated with local saints now largely forgotten outside their immediate districts. Mayo itself was a county of significant early Christian activity, home to monasteries that drew scholars from across Europe in the early medieval period, and small parish churches like the one at Kilgreana were often the local expressions of that broader tradition, serving rural communities whose lives were organised around the agricultural calendar and the liturgical year alike.

Beyond that, the available record for this particular site is sparse, and to say more with any confidence would require archival research rather than what can be responsibly summarised here. What remains is the place itself, a named site in the Mayo landscape where a church once stood, and the faint persistence of that fact in the syllables of the townland's name.