EGISTE, EGISTES, EGISTUS. Aegyptus had fifty sons and his brother Danaus had fifty daughters. He arranged marriages between his sons and nieces, but Danaus, fearing his brother's power, ordered his daughters to slay their husbands. When Hypermnestra disobeyed him, Danaus imprisoned her (Heroides XIV).

In The Legend of Ypermystra, Egistus is Ypermestra's father. Chaucer switches the parents and children. Egistus is false in love and has many daughters, but Ypermestra is his daughter dear. He agrees with his brother Danao to wed Ypermestra to Lyno, Danao's son, but Egistes commands her to slay Lyno. He calls her to his chamber on the wedding night and tells her that although he loves her, she shall die unless she does as he commands. He gives her a knife and commands her to slay Lyno because his dreams have told him that Lyno will cause his destruction. Ypermestra, however, spares Lyno's life, and they run away together. Ypermestra cannot run as fast as Lyno, and she is caught and imprisoned by her father. [Danao: Lyno: Ypermystra]

Egiste occurs as nominative in final rhyming position, LGW 2570, and as genitive in final rhyming position, LGW 2816, with unstressed final -e. Egistes occurs as dative, LGW 2600, and Egistus, nominative in initial position, LGW 2635. Egiste is a possible variant of Egisto in the Italian translation of the Heroides by Filippo Ceffi (c. 1320-1330); Chaucer may have also derived it from the Latin original.