Definition of "preceptor"

A man who had thought so much on the subjects of language and education was surely no ordinary preceptor.

c. 1793, Edward Gibbon, Memoirs, Penguin, published 1990, page 64

We shall resume our studies later on; but just now I am tired of playing the preceptor; and the eager thirst of my pupils for improvement does not console me for the slowness of their progress.

1905, George Bernard Shaw, The author's apology from Mrs. Warren's Profession, page 61