McGeachie (mag eacaro), MacGaugh (mag eacada), MacGeagh (mag eacada). McCaughan an Anglicized form of the Old Gaelic MacEachain, son of Eachain. An Ulster surname, recorded in the Counties of Antrim, Down, Londonderry and Tyrone. Some families of Mc Caughen changed their name to MacCaughey, itself an Anglicized form of the Ulster name Mac Eachaidh, son of the Horseman or Horse Lord. The Scots names MacGeachie and MacGeachy are also derived from Mag Eochaidh. McGachy, McGeachy. An anglicized version of the Gaelic 'Mac Eochaidh'. A surname in both Ulster and Scotland. William McGaheye settled in York, Virginia, in 1653, and Alexander McGeachy,
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