(clothing) An evening gown.

An event with a formal dress code.

(programming) A formal parameter.

(Oxbridge slang) Ellipsis of formal hall..

(uncountable) Formalin.

An acetal formed from formaldehyde.

Being in accord with established forms.

Official.

Relating to the form or structure of something.

Relating to formation.

Ceremonial or traditional.

Proper, according to strict etiquette; not casual.

Organized; well-structured and planned.

(mathematics) Relating to mere manipulation and construction of strings of symbols, without regard to their meaning.