Definition of "instructress"

[…] you must allow me to look upon you as my Scholar, in one Sense; as my Companion, in another; and as my Instructress, in a third.

1741, Samuel Richardson, letter VI, in Pamela, Volume IV, page 38

After a short pause Sir Thomas added with dignity, "Yes, let her home be in this house. We will endeavour to do our duty by her, and she will at least have the advantage of companions of her own age, and of a regular instructress."

1814 July, [Jane Austen], chapter I, in Mansfield Park: […], volume I, London: […] T[homas] Egerton, […], page 15

If she knew her instructress was poor and queer she also knew she was not nearly so ‘qualified’ as Miss Overmore, who could say lots of dates straight off […] .

1897, Henry James, chapter IV, in What Maisie Knew‎