What is the Latin word for idiom?

The usual Latin words for “idiom” are proprietās, idiōma, cārus; also ĭdĭōtismus. The right choice depends on the sense; see the distinctions below.

English → Latin

“idiom” in Latin

proprietāsquality, property, peculiarity, character; the legal position of an owner particularly if his property is encumbered wit idiōmaidiom (style of language)cārusdear, beloved; costly, expensive, valued ĭdĭōtismusthe common

Riddle & Arnold A Copious and Critical English–Latin Lexicon, 1864

idiom

proprietas: idioma, -atis (grammatical technical term, Charis.). The idioms of the Latin language, *quae Latinae linguae propria sunt. ☞ If IDIOM = language spoken anywhere (as in “the Bavarian idiom”), lingua or sermo must be used, or genus linguae (Quint.), dialectus (Suet.): *quod alicujus linguae proprium est. In post-Augustan prose, idiotismus denoted the vulgar dialect with all its peculiarities, Sen.

Quick answer

What is the Latin word for idiom?: The usual Latin words for “idiom” are proprietās, idiōma, cārus; also ĭdĭōtismus. The right choice depends on the sense; see the distinctions below.

Entry from J. E. Riddle & T. K. Arnold, A Copious and Critical English–Latin Lexicon (rev. C. Anthon, New York: Harper, 1864), digitised by Fergus J. P. Walsh, CC BY-SA 4.0; Latin markup adapted by latindictionary.co.