1.Definition: (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"
2.Definition: 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"
3.Definition: characteristic of or befitting a person in authority
4.Definition: logically deductive
5.Definition: refined or imposing in manner or appearance; befitting a royal court
6.Definition: represented in simplified or symbolic form