Which term is used to describe a variety of speech characterized by its own grammar or pronunciation linked to a specific geographical region?

The term that signifies a variety of speech associated with a certain geographical area, complete with its own unique grammar or pronunciation, is dialect. Dialects encompass not just pronunciation, or accent, but also distinct vocabulary and sentence structures that can vary significantly within a language depending on the region. For instance, English spoken in the Southern United States may have different grammatical rules and vocabulary compared to that used in the Northeastern part of the country, and these differences define it as a distinct dialect.

In contrast, an accent refers specifically to the way words are pronounced without necessarily incorporating variations in grammar or vocabulary, thus lacking the full scope of regional linguistic identity. An idiom represents a phrase whose meaning cannot be deduced from the literal words (e.g., "kick the bucket" meaning to die) but does not relate to geographical speech variations. A sociolect, meanwhile, refers to a variety of language used by a particular social class or group, rather than being tied to geographic factors.