Adjective
1. being in accord with established forms and conventions and requirements (as e.g. of formal dress);
"pay one's formal respects""formal dress""a formal ball""the requirement was only formal and often ignored""a formal education"2. characteristic of or befitting a person in authority;
"formal duties""an official banquet"3. (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"4. represented in simplified or symbolic form
5. logically deductive;
"formal proof"6. refined or imposing in manner or appearance; befitting a royal court;
"a courtly gentleman"