Open English Wordnet
Nouns
(n)quackan untrained person who pretends to be a physician and who dispenses medical advice (n)quackthe harsh sound of a duck Verbs
(v)quackutter quacking noises“The ducks quacked” (v)quackact as a medical quack or a charlatan Adjectives
(s)quackmedically unqualified“a quack doctor”