NIGHTBRINGER | The Arthurian Encyclopedia

Bun

‘Maiden’

Isolde’s sister, according to a Welsh Triad. Their father was named Culfanawyd.

She was apparently no more faithful to her husband, Fflamddwyn, than Isolde was to Mark.


Source
Triads of the Island of Britain (Welsh ”Triads”) | 11th century to 14th century