Regional words are the local terms for something. For example, a carbonated beverage may be called pop, soda, or soda pop depending on where you are. A thick sandwhich could be called a hero, grinder, sub, subway, hoagie, o po'boy.
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(jargon? - The questioner is asking about regional word pronunciation, and not about a specialized vocabulary or regional idiom. What distinguishes pronunciation of shared or standard words...