To make the usual sound of a duck: If you call someone a quack or a quack doctor, you mean that they claim to be skilled in medicine but are not. How to use quack in a sentence.
"Quacktastic Adventures Exploring the Playful World of Ducks" YouTube
The meaning of quack is to make the characteristic cry of a duck. A fraudulent pretender to medical skill. The harsh, throaty cry of a duck or any similar sound.
Quack (comparative more quack or quacker, superlative most quack or quackest) (quacker and quackest are rare, and probably used.
A person who dishonestly pretends to have medical skills.
