magister

from The Collaborative International Dictionary of English v.0.48

Magister \Ma*gis"ter\, n. [L. See {Master}.]
   Master; sir; -- a title of the Middle Ages, given to a person
   in authority, or to one having a license from a university to
   teach philosophy and the liberal arts.
   [1913 Webster]

from Bouvier's Law Dictionary, Revised 6th Ed (1856)

MAGISTER. A master, a ruler, one whose learning and position makes him 
superior to others, thus: one who has attained to a high degree, or 
eminence, in science and literature, is called a master; as, master of arts.

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