Idiomatic

a.	1.	Of or pertaining to, or conforming to, the mode of expression peculiar to a language; as, an idiomatic meaning; an idiomatic phrase.
	2.	Of or pertaining to, or of the nature of an idiom{3}; having a meaning that is peculiar to itself and not predictable from general rules.

Adj.

1.

idiomatic - of or relating to or conforming to idiom; "idiomatic English" Synonyms: idiomatical

idiom, idiomatical, parlance