id ‧ i ‧ om /ˈɪdiəm/ BrE AmE noun
[ Date: 1500-1600 ; Language: French ; Origin: idiome , from Greek idioma 'personal way of expressing yourself' , from idios ; ⇨ ↑ idiot ]
1 . [countable] a group of words that has a special meaning that is different from the ordinary meaning of each separate word. For example, ‘under the weather’ is an idiom meaning ‘ill’.
2 . [uncountable and countable] formal or technical a style of expression in writing, speech, or music that is typical of a particular group of people:
the new musical idiom