Formal

The term formal has a number of uses, including:

General

*relating to formality
*opposite of informal

ocial

* Formal occasion
** Formal attire worn on such occasions
** Formals are particular meals at some British universities
** In Australian or British English, a formal is the equivalent of the American prom dance.
** In American English, a "formal" is organized by a college or university organization, typically but not always a fraternity or sorority.
* Informal occasion (included as Informal redirect here); see Dress code (Western) for the distinctions between Formal, Semi-formal, and Informal
** Informal attire (not to be confused with Casual -- see Dress code (Western))

Philosophical

* relating to form, i.e. appearance rather than essence.
**relating to Formalism, i.e. emphasis on form over content or meaning.
*formal logic logical argument based only on the form and not on the meaning.
*Formal cause, Aristotle's intrinsic, determining cause.

Mathematics

*formal power series, a generalization of power series without requiring convergence, used in combinatorics;
*formal calculation, a calculation which is systematic, but without a rigorous justification;
*formal set theory as opposed to naive set theory;
*formal derivative, an operation on elements of a polynomial ring which mimics the form of the derivative from calculus.

Logic and Language

*formal system, an abstract means of generating inferences in a formal language;
**formal language, comprising the symbolic "words" or "sentences" of a formal system;
***formal grammar, a grammar describing a formal language;
**formal proof, a fully rigorous proof as is possible only in a formal system.

Computer science

*formal methods in computer science, including:
**formal specification describes what a system should do, not how it should do it
**formal verification proves correctness of a system

See also the Language section of Mathematics, above

Linguistic

*Formal equivalence word-for-word translation (especially of the Bible)

See also the Language section of Mathematics, above

Chemical

*A unit of concentration
*short or prefix form for formalin
*short or prefix form for formaldehyde
*synonym for dimethoxymethane

ee also

* Informal economy