Dyas Family History

English and Welsh: variant of Dayus from the personal name Deiws, a pet form of Dai and Dafydd, Welsh forms of David. In English counties bordering Wales, Dayus and Dyos were sometimes shortened to Day(e)s and Deyes, or altered to Dayhouse and Dyhouse through false association with the words deyhouse, dayhouse ‘dairy’ or deyehouse, dyehouse ‘dye-works’.

There is no medieval evidence that this name derived from either word. Dayhouse has since become extinct. Irish (Meath): perhaps a spelling adopted locally to Anglicize Irish Déise, see Dease, unless it is the name in 1 above.