provincialism

The quality of being provincial; having provincial tastes, mentality, manners.

The blacksmith's provincialism showed in his speech and manner

A word or locution characteristic of a region or district.

Prose is allowed less liberty in this respect; but no one nowadays would maintain that the adoption of a provincialism into the literary dialect is absolutely prohibited.

Synonym of regionalism: belief in the superiority of one's regional government; the belief that most or nearly all political power should be decentralized to provincial governments.