1A person who dishonestly claims knowledge of or skill in medicine; a pedlar of false cures.
Very common in 17th century; in later times largely superseded by the shortened form quack.
2In extended use: = "quack".
Late 16th century; earliest use found in Stephen Gosson (bap. 1554, d. 1625), anti-theatrical polemicist and Church of England clergyman. From early modern Dutch quacksalver person who cures with home remedies, further etymology uncertain: perhaps either from kwak scrap, remainder, rubbish (although this is first attested later: 1599 in Kiliaan as quack; from kwakken to fling down, apparently ultimately of imitative origin) + zalver person who cures by using ointments, or from kwakzalven to use or sell false cures (although this is first attested later: 1573 as quacsaluen; either from kwak (as above) + zalf (as above), or from †kwakzalf salve used as a home remedy (although this is first attested slightly later: 1578)). Compare Middle Dutch quacsalven, noun.