Ó Labhraidh Tréan, Armstrong, Mac Thréinfhir, MacGhillielaidir
Armstrong is a surname of Scottish borders origin. It derives from a Middle English nickname which meant someone with strong arms. In Ireland the name was adopted as an Anglicization of two Gaelic names from Ulster: Mac Thréinfhir (meaning "son of the strong man") and Ó Labhraidh Tréan (meaning "strong O'Lavery"). It has also been rendered in Gaelic as MacGhillielaidir.