ceremonious
Very formal and serious, following strict rules and traditions.
Ceremonious describes behavior or events that are formal, elaborate, and full of careful attention to proper procedures and rituals. When something is ceremonious, it follows traditional rules about how things should be done, with dignity and seriousness.
A ceremonious greeting might involve bowing deeply, shaking hands in a particular way, or using formal titles and phrases. A ceremonious dinner includes specific rules about which fork to use and how to properly address the hosts. When a judge enters a courtroom, everyone stands in a ceremonious show of respect for the law.
The word can describe both events and people. A ceremonious person acts with careful formality and pays close attention to proper etiquette and tradition. They might seem stiff or overly formal compared to someone more casual and relaxed.
Sometimes ceremonious has a slightly negative connotation, suggesting someone is being formal to the point of being stuffy or pompous. If a principal makes a ceremonious announcement about a minor schedule change, speaking in grand, formal language when a simple note would do, people might find it excessive.
Think of the difference between a casual birthday party and a ceremonious state dinner, or between waving hello to a friend and the ceremonious changing of the guard at Buckingham Palace. Ceremonious moments emphasize tradition, formality, and doing things the “proper” way.