The Collaborative International Dictionary of English v.0.48:

Monarchism \Mon"arch*ism\, n.
   The principles of, or preference for, monarchy.
   [1913 Webster]

WordNet (r) 3.0 (2006):

monarchism
    n 1: a belief in and advocacy of monarchy as a political system

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "monarchism":
   Bourbonism, Nazism, Toryism, backwardness, centralism,
   collectivism, communism, conservatism, conservativeness,
   constitutionalism, democratism, die-hardism, extreme right,
   extreme right wing, extreme rightism, fascism, federalism,
   feudalism, feudality, governmentalism, imperialism,
   know-nothingism, laissez-faireism, national socialism, neofascism,
   old school tie, parliamentarianism, parliamentarism, pluralism,
   political principles, radical rightism, reaction, reactionariness,
   reactionaryism, republicanism, rightism, royalism,
   social Darwinism, socialism, standpattism, statism,
   ultraconservatism, unprogressiveness