Fergus or Feargus is a common and one of the oldest known Scottish or Irish male given name derived from Old Irish, meaning "the strong (one)" or "the masculine (one)".[1][2]
As a surname, Ferguson or Fergusson is common across Scotland but particularly in Perthshire and Ayrshire. In Ireland, the Ferris family of County Kerry derives its surname from the patronymic Ó Fearghusa.