The Collaborative International Dictionary of English v.0.48:

Ceremonial \Cer`e*mo"ni*al\, n.
   1. A system of rules and ceremonies, enjoined by law, or
      established by custom, in religious worship, social
      intercourse, or the courts of princes; outward form.
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            The gorgeous ceremonial of the Burgundian court.
                                                  --Prescott.
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   2. The order for rites and forms in the Roman Catholic
      church, or the book containing the rules prescribed to be
      observed on solemn occasions.
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The Collaborative International Dictionary of English v.0.48:

Ceremonial \Cer`e*mo"ni*al\, a. [L. caerimonialis: cf. F.
   c['e]rimonial. See Ceremony.]
   1. Relating to ceremony, or external rite; ritual; according
      to the forms of established rites.
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            Ceremonial observances and outward show. --Hallam.
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   2. Observant of forms; ceremonious.

   Note: [In this sense ceremonious is now preferred.] --Donne.
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               He moves in the dull ceremonial track. --Druden.
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WordNet (r) 3.0 (2006):

ceremonial
    adj 1: marked by pomp or ceremony or formality; "a ceremonial
           occasion"; "ceremonial garb"
    n 1: a formal event performed on a special occasion; "a ceremony
         commemorating Pearl Harbor" [syn: ceremony, ceremonial,
         ceremonial occasion, observance]