Proto-Celtic *wesr-

→ Welsh gwanwyn (mention)

→ Irish earrach (derived)

→ Irish fáinleog (derived)

→ Irish arragh (derived(ga/gv))

→ Scottish Gaelic earrach (derived)

→ Scottish Gaelic ainleag (derived)

→ Cornish gwaynten (mention)

→ Cornish gwenton (mention)

→ Old Irish errach (derived)