convention
con-ven-tion
noun
A large formal meeting or assembly, often for a specific group or purpose.
"The party held its annual convention in Brighton."
noun
A widely accepted custom, practice, or rule in society or a group.
"It's a social convention to queue politely."
Thesaurus
Synonyms: conventionalism, conventionality, rule, formula, pattern, normal, convening
Antonyms: unconventionality