<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> Quackery or health fraud is the promotion of fraudulent or ignorant medical practices . A quack is a "fraudulent or ignorant pretender to medical skill" or "a person who pretends, professionally or publicly, to have skill, knowledge, qualification or credentials he or she does not possess; a charlatan or snake oil salesman". The term quack is a clipped form of the archaic term quacksalver, from Dutch: kwakzalver a "hawker of salve". In the Middle Ages the term quack meant "shouting". The quacksalvers sold their wares on the market shouting in a loud voice . </P> <P> Common elements of general quackery include questionable diagnoses using questionable diagnostic tests, as well as untested or refuted treatments, especially for serious diseases such as cancer . Quackery is often described as "health fraud" with the salient characteristic of aggressive promotion . </P>

Where does the word quack for doctor come from
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