A slave appointed by the Master to over see other usually younger or less experienced girls; "she rules when Free Persons are not present as the Master, but she is subject to his total authority", can be called "mistress" by the other girls, she may have switching rights over them as well.

Book 13: Explorers of Gor, page 78
Book 17: Savages of Gor, page 231
Book 22: Dancer of Gor, page 170, 211, and 380
Book 25: Magicians of Gor, page 123