Definition of Quack
Quack: 1) A practitioner who suggests the use of substances or devices for the prevention or treatment of disease that are known to be ineffective.
2) A person who pretends to be able to diagnose or heal people, but is unqualified and incompetent.
Last Editorial Review: 8/28/2013
Back to MedTerms online medical dictionary A-Z List
Need help identifying pills and medications?