List of English words of Brittonic origin
Few English words are definitively known to come directly from Brittonic, the language of the Celtic inhabitants of Britain prior to the Anglo-Saxon settlement of Britain. Words of Celtic origin have entered the English language by a number of different pathways, and some have been attributed to Brittonic as well as its descendants or other Celtic languages.
Source: Wikipedia — List of English words of Brittonic origin (CC BY-SA 4.0)