"Slieve" is an Anglicized form of the Irish word for mountain, sliabh. Bloom thinks in Calypso of some hills that bear his name ("Mine. Slieve Bloom"), and this range comes back in the company of some others near the end of Cyclops: "Slieve Aughty, Slieve Bernagh and Slieve Bloom."

John Hunt 2017

A view of the Slieve Bloom. Source:

The Mourne Wall climbing to the summit of Slieve Bearnagh. Source: Wikimedia Commons.