Patronymic was used by illegitimate royal children who were acknowledged as such by their fathers. The use of "Mac" in some form was prevalent in Scottish Gaelic, Irish and Manx, in all of which it denotes "son". "Mc" is also a frequent anglicisation in both Scotland and Ireland. In Ireland, the forms "Mag" and "M'" are encountered. The prefix "Mac" is used to form a patronym, such as "Mac Coinnich" – or the anglicized 'Mackenzie' – son of Coinneach/Kenneth. The female equivalent of "Mac" is "Nic", condensed from "nighean mhic" (in Scottish Gaelic) or "iníon mhic" (in Irish), both meaning daughter.
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