Princeton's WordNet

1. parlance, idiom(noun)

   a manner of speaking that is natural to native speakers of a language

2. dialect, idiom, accent(noun)

   the usage or vocabulary that is characteristic of a specific group of people

   "the immigrants spoke an odd dialect of English"; "he has a strong German accent"; "it has been said that a language is a dialect with an army and navy"

3. artistic style, idiom(noun)

   the style of a particular artist or school or movement

   "an imaginative orchestral idiom"

4. idiom, idiomatic expression, phrasal idiom, set phrase, phrase(noun)

   an expression whose meanings cannot be inferred from the meanings of the words that make it up

Kernerman English Learner's Dictionary

1. idiom(noun)ˈɪd i əm

   an expression that has a meaning different from the meaning of the individual words in it

   "Hit the roof" is an idiom meaning "get very angry."; idiomatic language that is difficult for foreigners to understand

Wiktionary

1. idiom(Noun)

   A manner of speaking, a way of expressing oneself.

2. idiom(Noun)

   A language or dialect.

3. idiom(Noun)

   Specifically, a particular variety of language; a restricted dialect used in a given historical period, context etc.

4. idiom(Noun)

   An artistic style (for example, in art, architecture, or music); an instance of such a style.

5. idiom(Noun)

   An expression peculiar to or characteristic of a particular language, especially when the meaning is illogical or separate from the meanings of its component words.

6. idiom(Noun)

   A programming construct or phraseology generally held to be the most efficient, elegant or effective means to achieve a particular result or behavior.

Origin: From idiome, and its source, idioma, from ἰδίωμα, from ἰδιοῦσθαι, from ἴδιος.

Webster Dictionary

1. Idiom(noun)

   the syntactical or structural form peculiar to any language; the genius or cast of a language

2. Idiom(noun)

   an expression conforming or appropriate to the peculiar structural form of a language; in extend use, an expression sanctioned by usage, having a sense peculiar to itself and not agreeing with the logical sense of its structural form; also, the phrase forms peculiar to a particular author

3. Idiom(noun)

   dialect; a variant form of a language

• idioomAfrikaans
• تَعْبير إصْطِلاحيArabic
• идиомBulgarian
• expressão idiomáticaPortuguese (BR)
• idiomCzech
• das IdiomGerman
• udtryksform; talemådeDanish
• ιδιωτισμόςGreek
• locución, modismo, frase hechaSpanish
• idioomEstonian
• اصطلاحFarsi
• idiomiFinnish
• locution idiomatiqueFrench
• צֵירוּף מִילִיםHebrew
• मुहावराHindi
• frazaCroatian
• idióma, kifejezés, szólásHungarian
• idiomIndonesian
• orðatiltæki, orðtakIcelandic
• espressione idiomaticaItalian
• 慣用句Japanese
• 숙어Korean
• idiomaLithuanian
• idiomātisks izteiciensLatvian
• ungkapanMalay
• idiomatische uitdrukkingDutch
• fast uttrykk, idiomNorwegian
• idiomPolish
• اصطلاحPersian
• اصطلاح، لهجه، دافادى ّخاص ډولPashto
• idiomaPortuguese
• expresie idiomaticăRomanian
• идиомаRussian
• idiom, fráza, ustálené slovné spojenieSlovak
• frazaSlovenian
• idiomSerbian
• idiom, uttryckSwedish
• สำนวนThai
• deyim, deyişTurkish
• 成語Chinese (Trad.)
• ідіома, ідіоматичний зворотUkrainian
• محاورہUrdu
• thành ngữVietnamese
• 成语Chinese (Simp.)