ceremony

A ritual, with religious or cultural significance.

To whom the Priest with naked armes full net Approching nigh, and murdrous knife well whet, Gan mutter close a certaine secret charme, With other diuelish ceremonies met:

In the fourteenth day of this month, at even, ye shall keep [the passover] in his appointed season: according to all the rites of it, and according to all the ceremonies thereof, shall ye keep it.

An official gathering to celebrate, commemorate, or otherwise mark some event.

a graduation ceremony, an opening ceremony

Promontory's "last spike" ceremony was so significant to the USA's history that it is still regularly re-enacted today, using replica locomotives that nose up to each other just as the originals did.

A formal socially established behaviour, often in relation to people of different ranks; formality.

[…] to feed were best at home; From thence the sauce to meat is ceremony; Meeting were bare without it.

Monsieur Bridet, notwithstanding his costume and his evident harrassment [sic], found in himself the presence of mind to remain the attentive manager, and with ceremony effected the proper introduction.

Show of magnificence, display, ostentation.

Meanwhile the winged Heralds, by command Of sovereign power, with awful ceremony And trumpet’s sound, throughout the host proclaim A solemn council forthwith to be held At Pandemonium […]

Immediately after her arrival, the queen rode forth to survey the camp and its environs: wherever she went, she was attended by a splendid retinue; and all the commanders vied with each other, in the pomp and ceremony with which they received her.

An accessory or object associated with a ritual.

[…] his ceremonies laid by, in his nakedness he appears but a man […]

[…] Well, believe this, No ceremony that to great ones ’longs, Not the king’s crown, nor the deputed sword, The marshal’s truncheon, nor the judge’s robe, Become them with one half so good a grace As mercy does.