The Collaborative International Dictionary of English v.0.48:

Mutessarif \Mu*tes`sa*rif"\, n. [Turk. & Ar. mute[,c]arif freely
   disposing of anything, master.]
   In Turkey prior to the revolution, an administrative
   authority of any of certain sanjaks. They were appointed
   directly by the Sultan.
   [Webster 1913 Suppl.]