Brythonic
1 of 2adjective
Bry·thon·ic bri-ˈthä-nik 
: of, relating to, or characteristic of the division of the Celtic languages that includes Welsh, Cornish, and Breton
Brythonic
2 of 2noun
: the Brythonic branch of the Celtic languages see Indo-European Languages Table
Word History
Etymology
Adjective
Welsh Brython Briton, Britons (from British Celtic *britton-) + -ic entry 1
First Known Use
Adjective
1884, in the meaning defined above
Noun
1879, in the meaning defined above