Mac Amhalghaidh variant forms of the name. A modern variant is Mac Amhalaí. Another is Mac Amhalaidh. Another variant is Mac Amhalghadha. Variant forms of "Mac Amhalghaidh" and "Mac Amhalghadha" include Mag Amhalghaidh and Mag Amhalghadha. "Mac Amhalghaidh" translates into English as "son of "Amhalghaidh"", or "son of "Amhalghadh"". The surname originated as a patronym, however it no longer refers to the actual name of the bearer's father. The personal name "Amhalghaidh", also spelt "Amhalghadh", is an old Gaelic name, and is of uncertain origin and meaning. "Mac Amhalghaidh" is a masculine surname. The form of this surname for unmarried females is
Eolais mac Biobhsach manuscripts going back almost two hundred years. O'Donovan claimed the family name ( "descendent of Eolais") is still found anglicised as "Olus" or "Olis". two instances of the surname corrupted as "Oelase" and "Olase", are found in the Irish Fiants for Leinster. The surname must be very rare. Eolais mac Biobhsach Eolais "mac Biobhsach" (alias " "knowledge", anglicized "Wallis", "Olis" or "Olus" ) was a chieftain of 10th century Gaelic Ireland. He is noted as the first "full chieftain of Conmaicne Réin". His descendants, "the Muintir Eolais", expanded into the territory of present day south county Leitrim, and parts of