Source : Webster's Revised Unabridged Dictionary (1913)

Republicanism \Re*pub"lic*an*ism\ (-?z'm), n. [Cf. F.
   r['e]publicanisme.]
   1. A republican form or system of government; the principles
      or theory of republican government.

   2. Attachment to, or political sympathy for, a republican
      form of government. --Burke.

   3. The principles and policy of the Republican party, so
      called [U.S.]

Source : WordNet®

republicanism
     n : the political orientation of those who hold that a republic
         is the best form of government