DUTHAC: The Scotticized form of Gaelic Dubhthach. The Old Irish name is Dubthach, mod. Irish Dubhthach, gen. Dubhthaigh as in Ua Dubhthaigh, usually Anglicized Duffy or O'Duffy, but rendered Duhig in county Cork, and Dooey, Dowey, and Duhy in Ulster. The Welsh is Dyfodwg. The earlier nominative is Dubthoch (as in Liber Armagh), and in an ogham inscription at Lamogue, county Waterford, Dovatuc-eas. In ON. spelled Dufthakr. Dubhthach was arch poet of King Laeghaire, converted by S Patrick. Dubhthach, coarb (comharba) of Columcille, died 7 October 938. Dubhthach Albanach (i.e. 'of Alba') 'chief soul friend of Ireland and Scotland,' d. 1065 (AU.). Duftach, 'sacerdos,' was one of the witnesses to confirmation of the church of Holy Trinity of Dunkeld to the Abbey of Dunfermline before 1169 (RD., p. 74). He is probably Dustah (f misread as long s), 'sacerdos et abbas,' probably a Culdee abbot of S. Serf's, who appears as witness to the settlement of a dispute between the Culdees of Lochleven and Robert Burgonensis in the reign of David I (RPSA., p. 118). As forename: Duthacus de Carnegy, 1410 (RER., I, 27). Duthac Ker was burgess of Edinburgh, 1482 (Neubotle, 304), and Duthac Rutherfurde was killed, 1495 (Trials, I, p. 20). From S. Duthac comes the Gaelic name of Tain, Baile Dhu'aich (Dhubhthaich).