Convention
Part of speech: noun
Definition: A meeting or gathering. A formal deliberative assembly of mandated delegates The convening of a formal meeting A formal agreement, contract or pact A treaty or supplement to such. A generally accepted principle, method or behaviour.
Example sentence: I was terrible in English. I couldn't stand the subject. It seemed to me ridiculous to worry about whether you spelled something wrong or not, because English spelling is just a human convention - it has nothing to do with anything real, anything from nature.
Conventionalism
Part of speech: noun
Definition: Adherence to social conventions; conventional behaviorA conventional act or constraintThe doctrine that logical or mathematical principles are simply the expression of conventions