The present parish of Lacken is made up of a union of the two ancient parishes of Lacken and Kilcummin. The present union of the parishes has existed since Penal Times and was brought about by the scarcity of priests then.
Leacan takes its name from the flat sloping surface on which the ancient church of Killogeary was built. This church would have been succeeded by at least one other building on the same site before the one now to be seen in ruins in Killogeary graveyard was built. Another possible derivation of the name might be that the original church was built from the thin limestone flags of the area.
Kilcummin takes its name from Cuimin, an early Saint of the locality in the 7th century. The Journal of the R.S.A.I. for 1898 dates Kilcummin church between the 9th and 10th centuries. The Ordnance Survey Letters place it in the townland of Ballinlena.