con·ven·tion 
(kən-vĕnshən)
(kən-vĕnshən)n.
1.
a. A formal meeting of members, representatives, or delegates, as of a political party, fraternal society, profession, or industry.
b. The body of persons attending such an assembly: called the convention to order.
2. 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.
3. General agreement on or acceptance of certain practices or attitudes: By convention, north is at the top of most maps.
4. A practice or procedure widely observed in a group, especially to facilitate social interaction; a custom: the convention of shaking hands.
5. A widely used and accepted device or technique, as in drama, literature, or painting: the theatrical convention of the aside.
[Middle English convencioun, from Latin conventiō, conventiōn-, meeting, from conventus, past participle of convenīre, to assemble; see CONVENE.]