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