Brittonic – this term is used to mean the insular P-Celtic before it lost its case and other final endings (general apocope). My usage reverses the usual habit of using Brythonic for this language and Brittonic for its successor(s). This preference is indicative of the fact that /tt/ existed prior to the change and <th> /θ/ thereafter, rather than the other way round, by spirantisation that formed part of British lenition.
British – (1) a more inspecific term than Brittonic and Brythonic that may be taken to include both; (2) its more usual modern meaning.
Brythonic – the P-Celtic language that succeeded Brittonic after its loss of final endings, which developed lenition (part voicing and part spirantisation) and various other changes such as the Accent Shift, i-affection, a-affection etc, in whatever order. Welsh and, if it differed from the former, Cumbric, formed one branch; South West Brythonic formed the other, which split into Breton and Cornish. It is at least possible that the Welsh of Gwent formerly had some South West Brythonic features, which might point to a former dialect continuum and/or some form of hybridisation.
Cymdeithas Cymru-Llydaw – the Welsh name of a cultural organisation based in Wales and Brittany, operating through the two countries’ native languages, aimed at strengthening linguistic and cultural links between the two sister cultures. Also known in Breton as Kevredigezh Kembre-Breizh.
general apocope – the loss of final endings, including case endings.
General Apocope – a fictional historical linguist superhero based in Aberystwyth, noted for his tactical linguistic assaults and, in his later career in military law, for his prowess in limiting case endings.
Keleier Breizh – the former name, in Breton, of the magazine Breizh-Llydaw published by the cultural organisation Kevredigezh Kembre-Breizh / Cymdeithas Cymru-Llydaw.
Kevredigezh Kembre-Breizh – the Breton name of a cultural organisation based in Wales and Brittany, operating through the two countries’ native languages, aimed at strengthening linguistic and cultural links between the two sister cultures. Also known in Welsh as Cymdeithas Cymru-Llydaw.
Newyddion Llydaw – the former name, in Welsh, of the magazine Breizh-Llydaw published by the cultural organisation Kevredigezh Kembre-Breizh / Cymdeithas Cymru-Llydaw.
P-Celtic – the central dialects of central Celtic, including the Brythonic languages descended from Brittonic, in which initial /kw became /p/.
Q-Celtic – the varieties of Celtic, including the modern Goidelic languages, Irish, Scots Gaelic and Manx, in which initial /kw did not become /p/. In Goidelic, the sound was reduced to /k/, losing the labial element, but otherwise remained.
South West Brythonic – the dialect of Brythonic that became Cornish and Breton, and may or may not have contributed to features of the Welsh of Gwent.