What does "quack" mean?

Quack: To make vain and loud pretensions; to boast. " To quack of universal cures." Hudibras.

Additional senses

  1. 2.To act the part of a quack, or pretender.
  2. 3.The cry of the duck, or a sound in imitation of it; a hoarse, quacking noise. Chaucer.
  3. 4.Etym: [Cf. Quacksalver.] A boastful pretender to medical skill; an empiric; an ignorant practitioner.
  4. 5.Hence, one who boastfully pretends to skill or knowledge of any kind not possessed; a charlatan. Quacks political; quacks scientific, academical. Carlyle.
  5. 6.Pertaining to or characterized by, boasting and pretension; used by quacks; pretending to cure diseases; as, a quack medicine; a quack doctor.

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