convention

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

• noun A formal meeting of members, representatives, or delegates, as of a political party, fraternal society, profession, or industry.
• noun The body of persons attending such an assembly.
• noun An agreement between states, sides, or military forces, especially an international agreement dealing with a specific subject, such as the treatment of prisoners of war.
• noun General agreement on or acceptance of certain practices or attitudes.
• noun A practice or procedure widely observed in a group, especially to facilitate social interaction; a custom.
• noun A widely used and accepted device or technique, as in drama, literature, or painting.

from The Century Dictionary.

• noun The act of coming together; coalition; union.
• noun A gathering of persons; a meeting; an assembly.
• noun Specifically A formal, recognized, or statutory meeting or assembly of men for civil or religious purposes; particularly, an assembly of delegates or representatives for consultation on important concerns, civil, political, or religious.
• noun An agreement or contract between two parties; specifically, in diplomacy
• noun General agreement; tacit understanding; common consent, as the foundation of a custom, an institution, or the like.
• noun A customary rule, regulation, or requirement, or such rules collectively; something more or less arbitrarily established, or required by common consent or opinion; a conventionality; a precedent.
• noun In civil law: In general, the agreement of several persons, who by a common act of the will determine their legal relations, for the purpose either of creating an obligation or of extinguishing one. in a narrower sense, the agreement of several persons in one and the same act of will resulting in an obligation between them.—
• noun In the fine arts, a generalization of nature which expresses certain phases of the actual and suppresses others, according to custom or tradition.
• noun In card-playing, a play adopted for convenience: as, in bridge, leading a heart when the pone doubles a no-trumper, or scoring spades without playing when the make is not doubled and the score is not 20 or better.

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

• noun The act of coming together; the state of being together; union; coalition.
• noun General agreement or concurrence; arbitrary custom; usage; conventionality.
• noun A meeting or an assembly of persons, esp. of delegates or representatives, to accomplish some specific object, -- civil, social, political, or ecclesiastical.
• noun (Eng. Hist) An extraordinary assembly of the parkiament or estates of the realm, held without the king's writ, -- as the assembly which restored Charles II. to the throne, and that which declared the throne to be abdicated by James II.
• noun An agreement or contract less formal than, or preliminary to, a treaty; an informal compact, as between commanders of armies in respect to suspension of hostilities, or between states; also, a formal agreement between governments or sovereign powers.

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

• noun A meeting or gathering.
• noun A formal deliberative assembly of mandated delegates
• noun The convening of a formal meeting
• noun A formal agreement, contract or pact
• noun international law A treaty or supplement to such.
• noun A generally accepted principle, method or behaviour.

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

• noun (diplomacy) an international agreement
• noun something regarded as a normative example
• noun a large formal assembly
• noun orthodoxy as a consequence of being conventional
• noun the act of convening