monitress

plural monitresses

1. archaicA female mentor or advisor; a female observer.First known use 18th c.

   Diana filled up all his heart: he felt as if by his union with her he had received a new and better soul. She was his monitress as he learned what were the true ends of life.

   1820, Mary Shelley, Mathilda, published 1959

   1 more example

   Maisie could feel his monitress stiffen almost with anguish against the increase of his spell and then hurl herself as a desperate defence from it into the quite confessed poorness of violence, of iteration.

   1897, Henry James, What Maisie Knew

2. datedA female monitor, or school leader.First known use 18th c.

   Miss Mitchell would certainly be most relieved to have a monitress who was capable of organising the juniors at games.

   1922, Angela Brazil, Monitress Merle