Something that always puzzled me about Breton was this 'z/zh' . It is obviously a sound shift which features only in modern Breton (not Old Breton - the one we need to use for place names), but where does it come from? The 'zh' spelling was introduced in 1941 to merge the representation of different dialect sounds: it represents /h/ in Vannetais and /js/ in the Tré gorrois, Cornouallais amd L é onard dialects. Dialects of Brittany Let's look at the Breton name for Brittany first - Breizh, which is pronounced 'brays' [/brejs/]. A l'Aise Breizh It comes from a common Brittonic Prythain which can be found in Old Breton [ Preden or Prydain ] , Welsh [ (Ynys) Prydain ] and Cornish [ Preden ] . In Latin this is Britannia and becomes, in French, Bretagne. In the old days the two Britains were Britannia Major (Great Britain) and Britannia Minor (Brittany/Little Britain/ Moindre Bretagne ). See here for an Irish language perspectiv...
The Origins and Place Names of Brittany