A glossary of Welsh common, personal, and place-names, purporting to trace their derivation from Greek.

'Llyfr Newydd Cyfochraeth ... Enwau, Ymadroddion, Traddodiad, Chwedloniaeth, a Llên, Groeg-Cymraeg, wedi eu Taflennu'n Gyfochrol, a'u hegluro ag enghreifftiau o'r clasuron. Y Gyferbyniaeth yn ol Arddull Deheubarth Cymru. Gan Gerwyn Wyn', being a glossary, with index, purporting to trace from Greek the derivation of Welsh (especially Carmarthenshire) common, personal, and place names. The volume was submitted for competition at the National Eisteddfod held at Caernarvon, 1935.