DALE (Dyf) Vall (1276). Earliest Record: Valle (1207). Meaning: the earliest form was FRENCH valee ‘valley`; the later Dale came from OE dæl or OSCAN dalr ‘valley'.
DEE / DYFRDWY (Riv) Dee (1043) / Deverdoe (10th century). Earliest Record: Deova (in Greek) (150). Earliest Welsh Record: Dubr Duiu (c. 1214). Meaning: from BRITISH deva (related to the word divine) ‘the goddess', thus ‘holy river'. In WELSH dwfr ‘water, river' and Dee.
DEFYNNOG (Pow) Devynock Meaning: it is possibly a personal name.
DEGANWY (Gwy) Deganwy Meaning: "the territory of the Decanae tribe". The original wooden castle was rebuilt in stone after 1210.
DENBIGH / DINBYCH (Clw) Dinbych (1269). Meaning: from WELSH din ‘fort' and bych (a side-form of bach) ‘small'. Headquarters of Llywelyn ap Gruffudd's brother Dafydd, who was executed in Shrewsbury.
DINAS (Dyf) Dinas Meaning: WELSH dinas ‘fort' or ‘camp'.
DINAS BRAN (Clw) Dinas Bran Meaning: WELSH dinas ‘fort' and possibly bron ‘hillside'. The stone castle was built, on the site of an earlier fort, in 1270.
DINAS POWYS (SGl) Dinas Powys Meaning: from WELSH dinas ‘fort' and the tribal name Powys (itself containing pau ‘a country').
DINEFWR (Dyf) Dynefwr Meaning: probably WELSH din ‘fort' and fawr ‘big'. It was the seat of Lord Rhys in the 12th century.
DINEIRTH (Gwy) Dineirth Meaning: WELSH din ‘fort' and, probably garth ‘promontory'; eirth ‘bears' is a possible, but unlikely, alternative.
DOLBADARN (Gwy) Dolpadarn Meaning: from WELSH dôl ‘meadow' and the personal name Padarn. The castle dates from c. 1200.
DOLFORWYN (Pow) Dolforwyn Meaning: probably WELSH ‘maiden's meadow`. The castle was held by Llywelyn ap Gruffudd.
DOLGELLAU (Gwy) Dolkelew (1254). Meaning: from WELSH dôl ‘loop, bend' in an earlier sense of ‘water meadow' and cellau, the plural of cell. The latter were either monastic or belonged to merchants.
DOLWYDDELAN (Gwy) Dolwyddelan Meaning: WELSH dôl ‘meadow' and the personal name Wyddelan. The castle keep dates from the late 12th century
DORE (Her) Dore (1147). Meaning: from the river name derived from BRITISH dubra, related to WELSH dwfr, ‘water'.
DRYSLWYN (Dyf) Dryslwyn Meaning: WELSH dryslwyn ‘thornbush, brambles'. The earliest record of the castle dates from 1246.
DYSERTH (Clw) Diserth Meaning: WELSH dyserth ‘wilderness, retreat'. Henry III's 1241 castle was destroyed by the Welsh in 1263.