Mac Murchaidh and Mac Murchadha (pronounced roughly MacMurakhy or MacMurafee and MacMuraha, or MacMurahow respectively) are Gaelic-Irish surnames. They were anglicised to MacMurphy, Murphy, MacMurrough, Murrow and Morrow in the 17th century after moving to the Armagh area. However it has different origins than the Wexford, Cork and Fermanagh County septs (see Murphy and Morrow).
The name Murchadh comes from the words "muir" (meaning sea) and "cath" (meaning battle). The name therefore comes to mean "Sea Warrior" and has been used in Ireland and Scotland. Over time the name has been Anglicised as Murchison, Murphy, Morrow, Morrowson, MacMurphy, MacMorrow, Murrow and MacMurchie but most commonly as Murphy and Morrow and most famously as MacMurrough. The names McMurchie, Murchison and Murphy normally come from Murchaidh, pronounced roughly Murahy whereas Morrow and Murrow tend to come from Murchadha, pronounced roughly Morahoe.
Mac Murchaidh was the surname of a branch of the Cenél nEógain. They were originally native to the district of Muintir Birn (now in the barony of Dungannon) and Tellach Ainbhith (in barony of Strabane) in Tír Eoghain, where they were chiefs of Siol Aodha. They take their surname from a Murchad of Siol Aodha, who was alive in the 10th or 11th century.
The Clann Birnn's is Bern mac Ruadrí mac Murchad mac Máel Dúin mac Áeda Alláin. Their corelatives are Mac Ruaidhrí (rendered as MacCrory, MacRory, Rodgers, Rogers) and Ó Firghil (now Friel, Freel).
The earliest reference to the name occurs in 1172, when Maol Maire Mac Murchadha toiseach Muinntire Birn do mharbhadh la h-Aedh Mac Aenghusa agus la Cloinn Aeda do Uibh Eachdach Uladh/Maol Maire Mac Murchadha, Lord of Muintir Birn, was slain by Aedh Mac Aenghusa and the Clann-Aodha of Uíbh Echach Ulaid.