1. (noun)ball, formal a lavish dance requiring formal attire
2. (noun)dinner dress, dinner gown, formal, evening gown a gown for evening wear
3. (adj)formal 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"
4. (adj)formal characteristic of or befitting a person in authority
"formal duties"; "an official banquet"
5. (adj)formal (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"
6. (adj)conventional, formal, schematic represented in simplified or symbolic form
7. (adj)formal logically deductive
"formal proof"
8. (adj)courtly, formal, stately refined or imposing in manner or appearance; befitting a royal court
"a courtly gentleman"