McCoy and Galloglass are both Anglicisations of terms from what language?
Gallowglass The gallowglasses (also spelt galloglass, gallowglas or galloglas; from Irish: "gall óglaigh" meaning foreign warriors) were a class of elite mercenary warriors who were principally members of the Norse-Gaelic clans of Scotland between the mid 13th century and late 16th century. As Scots, they were Gaels and shared a common background and language with the Irish, but as they had intermarried with the 10th century Norse settlers of western Scotland, the Irish called them "Gall Gaeil" ("foreign Gaels").
McGurn The name of McGurn, McGurran, Maggurran, Magorrin or Magurn, derives from an anglicisation of the older name of Mac-Samhradhain which can be spelled MacGauran, Magauran or McGovern. The owners of this name were chiefs of Teallach Eachach (translated as the tribe or region of the Ecchy) who had their territory in the Barony of "Tullaghagh", County Cavan. This name is pronounced by some people as "Somers", or "Summers" from the word "Samhradh" , which means summer.