preceptor

noun

1. A teacher or tutor.

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

   “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.”

2. (historical)The head of a preceptory of Knights Templar.
3. (US)A doctor who gives practical training to medical students, nurses etc.

   “Near-synonyms: mentor, professor”