Complex sentence: In Ireland, the name is an anglicisation of the Irish language surname "Ó Muiris" (also "de Muiris"), which is of Hiberno-Norman origin and indicates descendancy from a "Muiris".
Split into simpler sentences: In Ireland, the name is an anglicisation of the Irish language surname "Ó Muiris" (also "de Muiris"). Morris is of Hiberno-Norman origin and indicates descendancy from a "Muiris".