What term describes an untrained person who pretends to be a physician?

The term that describes an untrained person who pretends to be a physician is "quack." This term is commonly used to refer to individuals who falsely claim to have medical knowledge or credentials, often providing treatments or advice without any legitimate qualifications. Quacks can pose serious risks to public health, as they may promote ineffective or even harmful practices. The use of "quack" conveys a clear connotation of deceit and fraud in the medical field, distinguishing these individuals from professionals who are properly trained and licensed to practice medicine.

In contrast, other terms in the list do not accurately convey the intended meaning. The word "quizzical" typically describes a state of being puzzled or questioning something; "pristine" refers to something that is in its original condition or unspoiled; and "provisional" typically relates to something that is temporary or conditional, which does not align with the idea of someone impersonating a physician. Thus, "quack" is the most appropriate term to describe someone who falsely presents themselves as a medical professional.