It is an ancient ethnic name meaning 'foreigner', derived from the Old English pre 7th Century (Anglian) word 'walh', foreign, used by the Anglians of the Strathclyde Celts, the Britons, who survived as a separate group in Scotland well into the Middle Ages.Inch-Galbraith (noted by Pont in 1585 as Gabrachths yl [isle] na[med] Chastel]) in Loch Lomond was originally Elan-na-Gaul; island of the Gaul, according to Wm Fraser in his Chiefs of the Colquhoun....
" The following information (still a work-in-progress) has been pieced together from various on-line sources (from etymology, history, archaeology, palaeontology, and genetics) to provide an overall historical perspective on the migrations of our Waugh Family ancestors and the People that we came to be.
Some of the pieces of this "puzzle" seem to fit together quite well, while with some I'm waiting to see if they will fit together with any of the other pieces.
A recent "Viking hoard" discovered in Galloway and Dumfriesshire attests to the wealth of some of the Norse inhabitants.
Galloway (Gaelic: Gall-ghidheil; Latin: Gallovidia) is a region in southwestern Scotland comprising the counties of Wigtown and Kirkcubright.
The name means "foreign Gaels" referring to the Gaels of mixed Scandinavian and Gaelic origin who were once prevalent in the area.
Recent Big Y results (June 2017) indicate that the Waugh Y DNA haplogroup (I-FGC21732) may have originated in the south of Sweden in or around Gothia and Gotland.
The term was used by the ancient Germanic peoples to describe inhabitants of the former Western Roman Empire, who were largely romanised and spoke Latin or Celtic languages.
The adjectival form is attested in Old Norse valskr, meaning "French", Old High German walhisk, meaning "Romance", New High German welsch, used in Switzerland and South Tyrol for Romance speakers, Dutch Waals "Walloon", Old English welisċ, wlisċ, wilisċ, meaning "Romano-British", and Modern English Welsh.
They would, I proposed, have adopted the Cumbric language of their hosts, eventually switching to Gaelic after the Scottish conquest of Strathclyde in the eleventh century.