Source : Webster's Revised Unabridged Dictionary (1913)

Instructor \In*struct"or\, n. [L., a preparer: cf. F.
   instructeur.] [Written also {instructer}.]
   One who instructs; one who imparts knowledge to another; a
   teacher.

Source : WordNet®

instructor
     n : a person whose occupation is teaching [syn: {teacher}]