id·i·o·mat·ic 
(ĭd′ē-ə-mătĭk)
(ĭd′ē-ə-mătĭk)adj.
1.
a. Peculiar to or characteristic of a given language.
b. Characterized by proficient use of idiomatic expressions: a foreigner who speaks idiomatic English.
2. Resembling or having the nature of an idiom.
3. Using many idioms.
4. Peculiar to or characteristic of the style or manner of a particular group or people.
id′i·o·mati·cal·ly adv.