The Irish for Croagh is Cruach, or Cróch which means 'a rounded hill'. In the past Croagh was called Mayncroo. By 1109, Croagh had an abbey and two castles. After the defeat of James II at the Battle of the Boyne in 1690, Lewis says that James stayed one night at Amigan castle, which is now in ruins. According to Begley, in 1678, the then bishop of the diocese, Dr. James Dowley ordained priests from the famous school in Croagh.
Kilfinny is from the Irish Cill na Fionaí or Cill Finche, which means "the church of the wood". However, it is more commonly translated as "the church of St. Finneach". There were two female saints called St. Finneach. One founded a church in Knocktopher in Co. Kilkenny and the other came from what is now Co. Down. To confuse the issue further, the patron saint of Kilfinny is St. Ciarán. This St. Ciarán is from Clonmacnois and his feastday is on September 9th.