From French, “patois” translates literally as “rough speech.” It’s a linguistic term that can be used in two ways: either as a synonym for “jargon” or to describe the dialect of common people in a region. You can think of this as how people in a certain area speak when they’re at home or on the street, compared to how someone in the same region might speak in a professional context or in written communication. “Patois” isn’t a synonym for “slang,” but it does include slang vocabulary. “Patois” can also be used for a certain dialect that has developed distinct from the standard language, such as the Jamaican patois.