A female name. whether a Celtic or a German origin should be assigned to the name of the heroine of the Tristan romances is doubtful, though phonetically the German seems more likely. Essylt occurs early in Welsh; Isold, Isolt, a compound of is ‘ice’ and vald ‘rule’, occurs in Old German as early as the 8th C. It was a common christian name in the Middle Ages, owing its popularity to that of the Tristan romances. It is usually recorded in the latinized form Isolda, but the spoken forms of the name were derived from the French Iseut, Isaut. Ysolt occurs in 1201, Isowde, Isolde in the 15th C, but the usual English form of the name was Isot or Izot, which in turn was often latinized as Isota. C. W. Bardsley, Dictionary of English and WelshSurnames (pub. 1901) gives no fewer than 12 surnames derived fr it. He also gives an example of the christian name Izett in Ireland as late as 1891. A writer to N &. Q in 1880 stated that Isott was then still current in Somerset. Another N &. Q correspondent in 1877 wrote: ‘The name Isolda may be rare at the present day, but it has not fallen into disuse. I am well acquainted with a lady of that name, and I learned from her that it was an old family name in both her father’s and her mother’s family.’ Charlotte Mary Yonge, History of ChristianNames, 2 vols. 1863. Revised ed. 1884, however, seems to have regarded it as obsolete. Since then the name has had some revival, probably owing to the vogue of Wagner’s opera Tristan und Isolde.

Isolda Curia Regis Rolls 1199-1313, Hundred Rolls 1273, Feudal Aids 1346, Yorks Poll Tax of West Riding of Yorkshire 1379 1379 Ysolt Curia Regis Rolls 1201. Isota Yorks Poll Tax of West Riding of Yorkshire 1379 1379. Isott Cornish Church Registers 1576. Isylte Church Registers of St. James’s, Clerkenwell, 1551-1754 1612.

A definitely Romance form of Iseult. See Ysolt.