Source : Webster's Revised Unabridged Dictionary (1913)

Mastership \Mas"ter*ship\, n.
   1. The state or office of a master.

   2. Mastery; dominion; superior skill; superiority.

            Where noble youths for mastership should strive.
                                                  --Driden.

   3. Chief work; masterpiece. [Obs.] --Dryden.

   4. An ironical title of respect.

            How now, seignior Launce ! what news with your
            mastership ?                          --Shak.

Source : WordNet®

mastership
     n : the position of master