Noun

1. a sound made by a duck.

   Did you hear that duck make a quack?

2. a fraudulent doctor of medicine, an impostor who claims to have qualifications to practice medicine.

   That doctor is nothing but a lousy quack!

3. a charlatan.

   What a quack he is saying that's an organic Viagra ™!

4. (slang) a doctor.

Translations

• Dutch: kwak (1), kwakzalver (2, 3)
• French: coin-coin (1) m; charlatan m (2, 3); toubib m (4)
• Indonesian: kwek-kwek (1), gadungan (2, 3)
• Interlingua: quac (1)
• Italian: qua qua (1) m; ciarlatano (2, 3); dottore (4)
• Spanish: cuac (1); curandero m (2)

Adjective

1. falsely presented as having medicinal powers.

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

Verb

1. to make a noise like a duck.

   The more breadcrumbs I threw on the ground, the more they quacked.

   Do you hear the ducks quack?

Translations

• Dutch: kwaken
• French: faire coin-coin
• Interlingua: quaccar
• Italian: fare qua qua
• Spanish: decir cuac