of, according to, or following established or prescribed forms, conventions, etc: a formal document
2.
characterized by observation of conventional forms of ceremony, behaviour, dress, etc: a formal dinner
3.
methodical, precise, or stiff
4.
suitable for occasions organized according to conventional ceremony: formal dress
5.
denoting or characterized by idiom, vocabulary, etc, used by educated speakers and writers of a language
6.
acquired by study in academic institutions: a formal education
7.
regular or symmetrical in form: a formal garden
8.
of or relating to the appearance, form, etc, of something as distinguished from its substance
9.
logically deductive: formal proof
10.
philosophy
a. of or relating to form as opposed to matter or content
b. pertaining to the essence or nature of something: formal cause
c. (in the writings of Descartes) pertaining to the correspondence between an image or idea and its object
d. being in the formal mode
11.
denoting a second-person pronoun in some languages used when the addressee is a stranger, social superior, etc: in French the pronoun ``vous'' is formal, while ``tu'' is informal