>Various combined sites answer. The word Dutch comes from the old Germanic word theodisk, meaning 'of the people. Theodisk in modern German has become DEUTSCH and in Dutch has become the two forms: duits, meaning German, and diets meaning something closer to the existing Dutch people but no longer in general use. (Theodisk survives as tedesco in modern Italian.)
The English word Dutch has also changed with time. It was only in the early 1600s, with growing seafaring trade, gems and spices, cultural contacts and the rise of an independent country, that the modern meaning arose, i.e., 'designating the people of the Netherlands or their language'. Prior to this, the meaning was more general and could refer to any German-speaking area or the languages there (including the current Germany, Austria, and Switzerland as well as the Netherlands).