formal

adjective

refined or imposing in manner or appearance

courtly
being in accord with established forms and conventions and requirements (as e.g. of formal dress)
“pay one's formal respects”
of spoken and written language, adhering to traditional standards of correctness and without casual, contracted, and colloquial forms
“The paper was written in formal English.”
logically deductive
“formal proof”
characteristic of or befitting a person in authority
“formal duties”
represented in simplified or symbolic form

conventional

noun