IPA: /ˌsɛrəˈmoʊniəsnəs/
KK: /sɛrəˈmoʊniəsnəs/
The quality or state of being formal and respectful in behavior or actions, often associated with ceremonies or rituals.
The ceremoniousness of the wedding made it a memorable event for everyone involved.
Ceremoniousness is formed from "ceremonious" (from Latin "caerimonia", meaning a religious rite or ceremony) and the suffix "-ness" (meaning the state or quality of). The word describes the quality of being ceremonious, or marked by formality and ritual.
Think of 'ceremony' as a formal event, and '-ness' indicating a state. This helps you remember that 'ceremoniousness' refers to the quality of being formal and ritualistic.