formal

A lavish dance requiring formal attire.

A gown for evening wear.

Represented in simplified or symbolic form.

Refined or imposing in manner or appearance; befitting a royal court.

Being in accord with established forms and conventions and requirements (as e.g. of formal dress).

“pay one's formal respects”

“formal dress”

Characteristic of or befitting a person in authority.

“formal duties”

Logically deductive.

“formal proof”

(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”