Plural of ceremonial; formal rituals, ceremonies, or religious observances, or the objects and garments used in performing them.
From Latin 'caerimonia' via French 'cérémonial'. The plural form reflects the use of 'ceremonial' as a countable noun referring to specific rituals or ceremonial systems.
Ceremonials were so important to medieval societies that entire books—called 'ceremonials'—were written just to document the proper way to perform religious and royal rituals, showing how obsessed people were with getting every gesture exactly right.
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