The Brythonic leids (kent as the Brittonic leids or Breetish leids forby) form ane o the twa brainches o the Insular Celtic faimily o leids, the ither being Goidelic. The name Brythonic wis derived by Sir John Rhys frae the Welsh wird Brython, meanin an indigenous Briton as contrair tae an Anglo-Saxon or Gael. The name Brittonic comes ultimately frae the name Prettanic recorded by Greek authors for the Breetish Isles. Some authors reser the term Brittonic for the modified later Brythonic leids efter aboot the year 600.
Thae leids hae been spoken in the Breetish Isles (includin the Isle o Mann) sin at laist the Airn Age till the day, oreeginally as the majority leids but nou as minority anes in Wales an Cornwall. In Ireland, the Isle o Mann an Scotland the Brythonic leids hae been replaced by Goedelic anes. By emigration there are communities o Brythonic leid speakers in Brittany, an Patagonia an aw.