AskDefine | Define informal

Dictionary Definition

informal adj
1 not formal; "conservative people unaccustomed to informal dress"; "an informal free-and-easy manner"; "an informal gathering of friends" [ant: formal]
2 not officially recognized or controlled; "an informal agreement"; "a loose organization of the local farmers" [syn: loose]
3 used of spoken and written language [ant: formal]
4 having or fostering a warm or friendly atmosphere; especially through smallness and informality; "had a cozy chat"; "a relaxed informal manner"; "an intimate cocktail lounge"; "the small room was cozy and intimate" [syn: cozy, intimate]

User Contributed Dictionary




  1. Not formal or ceremonious; casual.
    an informal get-together
  2. Not in accord with the usual regulations; unofficial.
    an informal agreement
  3. Suited for everyday use.
    informal clothes
  4. In the context of "of language": Reflecting everyday, non-ceremonious usage.


not formal or ceremonious; casual
  • Czech: neformální

See also

Extensive Definition

The term formal has a number of uses, including:




  • 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.


  • 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 proof, a fully rigorous proof as is possible only in a formal system.

Computer science

See also the Language section of Mathematics, above


See also the Language section of Mathematics, above


informal in German: Formalität
informal in French: Formel
informal in Italian: Formalità
informal in Dutch: Formeel
informal in Simple English: Formal

Synonyms, Antonyms and Related Words

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