The Collaborative International Dictionary of English v.0.48:

Ritualistic \Rit`u*al*is"tic\, a.
   Pertaining to, or in accordance with, a ritual; adhering to
   ritualism.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ritualistic
    adj 1: of or characterized by or adhering to ritualism; "a
           feudal or ritualistic society"; "the ritualistic killing
           of a sheep"

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "ritualistic":
   High-Church, baptismal, ceremonial, ceremonious, conventional,
   decorous, eucharistic, formal, formular, formulary, hieratic,
   liturgic, liturgistic, paschal, pompous, ritual, sacerdotal,
   sacramental, sacramentarian, solemn, stately, well-mannered