pre·cep·tor 
(prĭ-sĕptər, prēsĕp′tər)
(prĭ-sĕptər, prēsĕp′tər)n.
1. A teacher; an instructor.
2. An expert or specialist, such as a physician, who gives practical experience and training to a student, especially of medicine or nursing.
3. The head of a preceptory.
[Middle English, from Latin praeceptor, from praecipere, to teach; see PRECEPT.]
pre′cep·tori·al (prē′sĕp-tôrē-əl) adj.
pre′cep·tori·al·ly adv.