The Oxford Thesaurus An A-Z Dictionary of Synonyms - conventionn.

1) assembly, meeting, gathering, congregation, congress, conference, symposium, council, conclave, diet, synod, seminar: The annual convention of cat fanciers will take place in June. 2 rule, practice, custom, tradition, usage, formality, conventionalism: According to convention, this year's vice-president becomes president next year.