The Collaborative International Dictionary of English v.0.48:

Royalist \Roy"al*ist\, n. [Cf. F. royaliste.]
   An adherent of a king (as of Charles I. in England, or of the
   Bourbons in france); one attached to monarchical government.
   [1913 Webster]

         Where Ca'ndish fought, the Royalists prevailed.
                                                  --Waller.
   [1913 Webster]

WordNet (r) 3.0 (2006):

royalist
    n 1: an advocate of the principles of monarchy [syn:
         monarchist, royalist]
    2: a royalist supporter of Charles I during the English Civil
       War [syn: Cavalier, Royalist]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "royalist":
   Bircher, Bourbon, Tory, conservatist, conservative, diehard,
   extreme right-winger, hard hat, imperialist, monarchist,
   radical right, reactionarist, reactionary, reactionist, right,
   right wing, right-winger, rightist, social Darwinist, standpat,
   standpatter, ultraconservative