Lismore (lĭsmôrˈ, lĭz–) [key], town (1991 pop. 715), Co. Waterford, S Republic of Ireland, on the Blackwater River. It is a market town with a salmon fishing industry. In the 7th cent., St. Carthagh founded a monastery there. By the 8th cent. it was a famed center of learning. Lismore Castle, which has been restored, was built under Prince (later King) John in 1185. Robert Boyle was born in Lismore.