They mean foreigner or outsider or even 'next to'
I seriously think that the whole Celtic region was referred to as the "outsiders" or Galatia.
I'll repeat a few earlier posts I made on the Applied Epistemology site as they seem to be very on topic here:
Barb -Female- Latin The foreigner or stranger. From the name Barbara.
Barbara- Female Latin- The foreigner or stranger.
WALE (British). "Foreign" (Germanic); or, "choice, excellent, noble" (Middle English); or, "ridge, bank".
GERMAN (British). "German." The term 'German' is a Celtic word meaning either "neighbour" or "battle-cry."
And MOST interestingly with W = G
Gaul in Latin is Gallia
the Welsh noun plural - les Gallois - The Welsh.
So Wales was known as the foreigners before the English coined the word Wal for them!!! WOW now that is odd.
The whole of Britain at the end of the last Ice Age was becoming detached from mainland Europe, there was little distinction between the tribes until the English Channel filled.
Gal- Britain (post Ice age)
Wal- Britain (pre Celtic? ie Picts, Viking etc)
Portugal, Galicia, Gaul (France), Cornwall (Cornugales - Cornu=horn), Gales (Wales)
British lands end Fingal? End of Britain?