Dictionary of Medieval Names
from European Sources

Gwyn m. Welsh gwyn 'fair, white; blessed' from Proto-Celtic *windo 'white'.

Cf. Wynn for an English cognate.

Wales
Latin
1216xc1226 Gwin (gen) Pryce-1st; 1456 Gwyn (nom) ArchCambIII p. 258; 1457 Gwyn (nom) ibid. p. 259
Cite as: S.L. Uckelman. "Gwyn". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2017, no. 1. http://dmnes.org/2017/1/name/Gwyn.