The Collaborative International Dictionary of English v.0.48:

Persism \Per"sism\, n.
   An ancient Persian religion, esp. as represented by the Magi;
   a form of Zoroastrianism.
   [1913 Webster + PJC]

         This system we shall call 'Persism', in order to free
         ourselves of the popular associations still connected
         with such terms as magism, Parseeism, and so forth;
         meaning by 'Persism' the teaching of Zarathustra as it
         affected the Greek and Latin world.      --E. Vernon
                                                  Arnold.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Persism \Per"sism\, n.
   A Persian idiom.
   [1913 Webster]