ceremony

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A formal act or set of acts performed as prescribed by ritual or custom.
• noun A conventional social gesture or act of courtesy.
• noun A formal act without intrinsic purpose; an empty form.
• noun Strict observance of formalities or etiquette.

from The Century Dictionary.

• To confirm or join by a ceremony.
• noun A religious observance; a solemn rite.
• noun The formalities observed on some solemn or important public or state occasion in order to render it more imposing or impressive: as, the ceremony of crowning a king, or of laying a foundation-stone; the ceremony of inaugurating the President of the United States.
• noun A usage of politeness, or such usages collectively; formality; a punctilious adherence to conventional forms; punctilio.
• noun A ceremonial symbol or decoration.
• noun A sign or portent; a prodigy.
• noun An officer in many European cathedrals whose business it is to see that all the ceremonies, vestments, etc., peculiar to each season and festival are observed in the choir.
• noun Synonyms Form, Ceremony, Rite, Observance. Form is the most general of these words; it is impossible to join in worship without the use of some forms, however simple; we speak of legal forms, etc. Ceremony is a broader word than rite, in that a rite is always solemn and either an act of religion or suggestive of it, as marriage-rites, the rites of initiation, while ceremony goes so far as to cover forms of politeness. A rite is generally a prescribed or customary form, while a ceremony may be improvised tor an occasion: as, the ceremony of laying a corner-stone or opening a new bridge. Observance is primarily a compliance with a requirement, as in religion, where the word was applied to the act of compliance; as, the observance of the sabbath.

from the GNU version of the Collaborative International Dictionary of English.

• noun Ar act or series of acts, often of a symbolical character, prescribed by law, custom, or authority, in the conduct of important matters, as in the performance of religious duties, the transaction of affairs of state, and the celebration of notable events.
• noun Behavior regulated by strict etiquette; a formal method of performing acts of civility; forms of civility prescribed by custom or authority.
• noun obsolete A ceremonial symbols; an emblem, as a crown, scepter, garland, etc.
• noun obsolete A sign or prodigy; a portent.
• noun an officer who determines the forms to be observed, or superintends their observance, on a public occasion.
• noun not to be ceremonious; to be familiar, outspoken, or bold.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A ritual with religious significance.
• noun An official gathering to celebrate, commemorate, or otherwise mark some event.
• noun Formal socially-established behaviour often in relation to people of different ranks.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any activity that is performed in an especially solemn elaborate or formal way
• noun the proper or conventional behavior on some solemn occasion
• noun a formal event performed on a special occasion