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 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.
• 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.—

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