The name of the tragic mistress of Tristan in the Arthurian romances. There are several versions of the story. The main features are that the beautiful Isolde, an Irish princess, is betrothed to the aged King Mark of Cornwall. However, through accidentally drinking a magic potion, she and the young Cornish knight Tristan fall in love, with tragic consequences. The story has exercised a powerful hold on the European imagination. The name was relatively common in Britain in the Middle Ages, but is much rarer today.