The Collaborative International Dictionary of English v.0.48:

Monarchic \Mo*nar"chic\, Monarchical \Mo*nar"chic*al\, a. [F.
   monarchique, Gr. ?.]
   Of or pertaining to a monarch, or to monarchy. --Burke. --
   Mo*nar"chic*al*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

monarchical
    adj 1: having the characteristics of or befitting or worthy of a
           monarch; "monarchical gestures"; "monarchal pomp" [syn:
           monarchal, monarchical]
    2: ruled by or having the supreme power resting with a monarch;
       "monarchal government"; "monarchical systems" [syn:
       monarchal, monarchical, monarchic]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "monarchical":
   absolute, aristocratic, authoritarian, autocratic, autonomous,
   bureaucratic, civic, civil, constitutional, democratic, despotic,
   dictatorial, dynastic, fascist, federal, federalist, federalistic,
   governmental, gubernatorial, heteronomous, imperatorial,
   imperatorious, imperial, imperious, kinglike, kingly, majestic,
   matriarchal, matriarchic, monarchal, monarchial, monarchic,
   monocratic, official, oligarchal, oligarchic, parliamentarian,
   parliamentary, patriarchal, patriarchic, pluralistic, political,
   princelike, princely, purple, queenlike, queenly, regal,
   republican, royal, self-governing, sovereign, theocratic,
   totalitarian