ceremonious

Short definition from Wiktionary

Adjective

1. 1
   According to the required or usual ceremonies, formalities, or rituals; specifically (Christianity, obsolete), to ceremonial laws in the Bible.
2. 2
   Involving much ceremony; ostentatious, showy.
3. 3
   Of a person: fond of ceremony or ritual, or of observing strict etiquette or formality; punctilious.
4. 4
   Synonym of ceremonial (“of, relating to, consisting of, or used in a ceremony or rite”); formal, ritual.