A dishonest or unethical person, especially a lawyer who uses questionable or dirty tricks.
Possibly from German 'Scheißer' (one who defecates), though the etymology is debated; may also derive from the surname of a disreputable New York lawyer in the 1840s named Scheuster.
The word 'shyster' is so associated with dishonest lawyers that courts have actually discussed whether using it violates professional conduct codes—proving that a single word can carry powerful cultural baggage!
Complete word intelligence in one call. Free tier — 50 lookups/day.