What is "dunamase"

Dunamase or The Rock of Dunamase ( "fort of Másc") is a rocky outcrop in the townland of Park or Dunamase in County Laois. The rock, above a flat plain, has the ruins of Dunamase Castle, a defensive stronghold dating from the early Hiberno-Norman period with a view across to the Slieve Bloom Mountains. It is near the N80 road between the towns of Portlaoise and Stradbally.