ISAUDE, ISAWDE, YSOUDE. Yseult was an Irish princess, daughter of the king and queen of Ireland. King Mark of Cornwall fell in love with her hair, one strand of which he saw in the beak of a bird perched on his window, and sent his nephew Tristan to find the owner of the hair. Tristan reached Ireland and slew a dragon that was ravaging the countryside. Wounded in the fight, he was taken to the palace to be healed of his wounds by the queen and her daughter. The princess, Yseult, recognized him as the slayer (on a previous visit) of the Morholt, her uncle. As she admired his sword, she was able to match the piece taken from the Morholt's skull with the notch in Tristan's weapon. Although she had sworn vengeance on the Morholt's killer, when she saw Tristan's beauty as he lay in the bath, she could not carry out her vow. Her father commanded Yseult to accompany Tristan back to Cornwall to become Mark's bride, but on the voyage they accidentally drank the magic potion prepared by her mother for the wedding night and fell irrevocably in love. The first literary version of the story was composed c. 1150, possibly in Anglo-Norman; about 1160, the Welsh poet Thomas made it a tale of courtly love. A German version appeared about 1175 by Eilhart von Oberge and a French one about 1200 by Beroul. The version of Gottfried von Strassburg (fl. 1210) is based on Thomas's story.

Not even the beautiful Isawde can warn people against love, HF III.1793-1799. Isaude is love's martyr, PF 288-292. Ysoude must hide her beauty before Alceste's, LGW F 254-255, LGW G 208-209. [Tristram]

The forms are ME variants of OF Yseut. Isaude occurs once medially, PF 290; Isawde occurs once in final rhyming position, HF III.1796; Ysoude occurs twice medially, LGW F 254, LGW G 208.