Dictionary of Medieval Names
from European Sources

Gwynhoiarn m. Old Breton uuin, uuen, Middle Welsh guin, gwynn, guen 'sacred, pure, blessed; white' + Old Breton (ho)iarn 'iron'.

France
Latin
833 Uuinhoiarn (nom) CartRed VIII
Cite as: S.L. Uckelman. "Gwynhoiarn". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2017, no. 1. http://dmnes.org/2017/1/name/Gwynhoiarn.