The Collaborative International Dictionary of English v.0.48:

Zionism \Zi"on*ism\, n. [Zion + -ism.]
   Among the Jews, a theory, plan, or movement for colonizing
   their own race in Palestine, the land of Zion, or, if that is
   impracticable, elsewhere, either for religious or
   nationalizing purposes; -- called also Zion movement. --
   Zi"on*ist, n. -- Zi`on*is"tic, a.
   [Webster 1913 Suppl.]