Gahan (surname) Irish language "Mac Gaoithín", meaning "son of "Gaoithín"", although the more common Anglicised form of this Gaelic name is "McGeehan" in Ulster. Gahan (surname) Gahan (and its variant Gahame) is a surname with several different origins. One origin of the surname is from a reduced form of "McGahan", which is in turn an Anglicised form of the Irish language "Mac Eacháin", meaning "son of "Eachán"". Another origin of the name, in Leinster, is from a reduced form of the Irish language "Ó Gaoithin", meaning "descendant of "Gaoithín"". The personal name "Gaoithín" is a diminutive of "gaoth", meaning "wise", or "wind".
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