SYNONYMY NOTE: quack 1, charlatan both apply to a person who unscrupulously pretends to knowledge or skill he or she does not possess, but , quack 2 almost always is used of a fraudulent or incompetent practitioner of medicine; , mountebank, in modern use, applies to a person who resorts to cheap and degrading methods in his or her work, etc.; , impostor applies especially to a person who fraudulently impersonates another and, more generally, to anyone who is a hypocrite; , faker is an ...