Save Type Surname Usage Scottish, Irish, English, Dutch (Anglicized), German (Anglicized) Other Forms FormsDau, Douw, Daw, McDow Meaning & History Scottish (also found in Ireland): reduced form of McDow. This surname is borne by a sept of the Buchanans.English: variant of Daw.Americanized spelling of Dutch Douw, an Old Frisian personal name.Americanized spelling of German Dau.