Of a thing: characteristic of the countryside or country life; of a type or style appropriate to the country; especially plain, simple; crude.

Of speech, writing, behaviour, etc.: characteristic or typical of country people; especially (depreciative) unrefined, vulgar.

Of a person: boorish; unsophisticated; = "rustic".

A person who lives in the countryside (typically implying ignorance or lack of sophistication); a yokel; = "rustic".