quack Definition

quack¹
noun

1. The noise that a duck makes.

verb, intr quacked, quacking

1. Said of a duck: to make this noise.
2. To talk in a loud silly voice.

Derivative: quacker
noun

Etymology: 17c: imitating the sound.

---

quack²
noun

1. Someone who practises medicine or who claims to have medical knowledge, but who has no formal training in the subject.
2. colloq, often derog
A term for any doctor or medical practitioner, etc.
3. Anyone who pretends to have a knowledge or skill that they do not possess.

Thesaurus: fraud, swindler, impostor, charlatan, cheat, mountebank.

Derivative: quackish
adj

Etymology: 17c: from Dutch quacksalver, from kwakken to quack + salf an ointment.