Geilissa was Orestes'
old nurse. According to one story, she sent her own son to bed in the royal nursery so that he would be killed by Aegisthus instead of
Orestes (who was then only ten years old). Her name means 'smiler', 'laugher' from gelao, 'to laugh'. This is an attractive name for an old nurse. In other accounts, she is named as Arsinoë or Laodamia.
