formal >> ˈfɔːm(ə)l
Definition: [adjective] done in accordance with convention or etiquette; suitable for or constituting an official or important occasion.
Example: a formal dinner party
Definition: [adjective] officially sanctioned or recognized.
Example: a formal complaint
Definition: [adjective] of or concerned with outward form or appearance as distinct from content.
Example: I don't know enough about art to appreciate the purely formal qualities
Definition: [noun] an evening dress.
Example: cocktail parties every night so the ladies can show off their formals