Ídiom. n.s. [idiome, French; ἰδίωμα.] A mode of speaking peculiar to a language or dialect; the particular cast of a tongue; a phrase; phraseology.
He did romanize our tongue, leaving the words translated as much Latin as he found them; wherein he followed their language, but did not comply with the idiom of ours. Dryden.
Some that with care true eloquence shall teach,
And to just idioms fix our doubtful speech. Prior.