Pennsylvania Dutch
Contrary to popular belief, the word "Dutch" in "Pennsylvania Dutch" is not a mistranslation, but rather a corruption of the Pennsylvania German endonym "Deitsch", which means "Pennsylvania Dutch / German" or "German". Ultimately, the terms Deitsch, Dutch, Diets and Deutsch are all cognates of the Proto-Germanic word meaning "popular" or "of the people". The continued use of "Pennsylvania Dutch" was strengthened by the Pennsylvania Dutch in the 19th century as a way of distinguishing themselves from later (post 1830) waves of German immigrants to the United States. Further, the Pennsylvania Dutch referred to themselves as "Deitsche" and to Germans as "Deitschlenner" (literally "Germany-ers", compare "Deutschland-er") whom they saw as a related but distinct group.