When you think of the word rustic, think of the rural country. This word can be given a positive or a negative spin depending on how you use it; a rustic inn, for example, might be quaint or it might be virtually uninhabitable.
The words rustic and "rural" spring from the same ancient root: *rur-, which means "open space" in the hypothetical ancestor language Proto-Indo-European. In early usage, these two words were used interchangeably, but now, rural is used to describe locations –- "rural community," "rural location" — while rustic refers to the unrefined qualities associated with country life. The best antonym is cosmopolitan, which implies the sophistication and worldliness of city life.