Englishidiom
noun
1 ‘Far out,’ she replied, using a rather dated idiom:
expression, idiomatic expression, turn of phrase, set phrase, fixed expression, phrase;
formal locution.
2 the poet's idiom is elegantly terse:
language, mode of expression, style of speech, speech, talk, -speak, way/manner of speaking, usage, phraseology, phrasing, choice of words, vocabulary, parlance, tongue, vernacular, jargon, patter, argot, patois, cant;
French façon de parler;
informal lingo;
formal locution.
idiom Oxford Dictionary of English