In the United States, the word "Dutch" remained somewhat ambiguous until the start of the 19th century. Generally, it referred to the Dutch, their language or the Dutch Republic, but it was also used as an informal monniker (for example in the works of James Fenimore Cooper and Washington Irving) for people who would today be considered Germans or German-speaking, most notably the Pennsylvania Dutch. This lingering ambiguity was most likely caused by close proximity to German-speaking immigrants, who referred to themselves or (in the case of the Pennsylvania Dutch) their language as "Deutsch" or "Deitsch", rather than archaic use of the term "Dutch"