quack

The sound made by a duck.

“Did you hear that duck make a quack?”

To make a noise like a duck.

“Do you hear the ducks quack?”

A fraudulent healer or incompetent professional; especially, a doctor of medicine who makes false diagnoses or inappropriate treatment; an impostor who claims to have qualifications to practice medicine.

“That doctor is nothing but a lousy quack!”

A charlatan.

A doctor.

To practice or commit quackery (fraudulent medicine).

To make vain and loud pretensions.

Falsely presented as having medicinal powers.

“Don't get your hopes up; that's quack medicine!”