Shyster, an American slang term for a shady, disreputable lawyer, is first recorded in
l846. Various authorities list a real New York advocate as a possible
source, but this theory has been disproved by Professor Gerald L. Cohen of
the University of Missouri-Rolla, whose long paper on the etymology I had
the pleasure of reading. Shakespeare's moneylender Shylock has also been
suggested, as has a racetrack form of the word shy ie., to be shy money
when betting. Some authorities trace shyster to the German Scheisse,
"excrement," possibly through the word shicir, "a worthless person," but
there is no absolute proof for any theory. In any case, shady lawyers in
New York have been called shysters since the l840s.