The OED definition for 'shyster':
slang.
1. ‘A lawyer who practises in an unprofessional or tricky manner; especially, one who haunts the prisons and lower courts to prey on petty criminals; hence, any one who conducts his business in a tricky manner’ (Funk's Stand. Dict. 1895). Also attrib. or adj. orig. and chiefly U.S.
1844 G. WILKES Mysteries of Tombs 44/1 He is consulted by the magistrates on all important points of law, and the inferior shysters look upon him with a reverence approaching veneration. 1849 G. G. FOSTER New York in Slices 20 He must..wait next day for the visits of the ‘shyster’ lawyersa set of turkey-buzzards whose touch is pollution and whose breath is pestilence. 1856 Knickerb. Mag. Apr. XLVII. 434 (Thornton Amer. Gloss.) If these two ‘shuysters’ on the other side could get one more drink down your throat, you couldn't travel at all. 1857 N.Y. Tribune 13 Mar. (Bartlett 1860) The shysters, or Tombs lawyers, were on hand, and sought to intercede for their clients. a1860 N.Y. Tribune (ibid.), When a man or woman is thrown into prison, a shyster leech gets access to him, and extorts from him his last cent under the pretence of obtaining his liberation. 1877 BLACK Green Past. xli, They..looked on a prominent civic official as a mere shyster. 1902 BOOTHBY Uncle Joe's Legacy 98 The shyster lawyer. 1943 M. H. HARRIS Vegetative Eye 15 Not to Memory, with its shyster lackey, Association. 1952 Manch. Guardian Weekly 19 June 3 They call Taft's ‘shyster methods’ so necessary. 1961 Listener 14 Dec. 1046/1 A solicitor's chief clerk who persuades his shyster employer to leave the country to avoid embezzlement charges. 1981 J. WAINWRIGHT All on Summer's Day 31 The shyster lawyers..swear blind the client's been manhandled while in police custody.
2. Austral. Alteration of SHICER.
1938 X. HERBERT Capricornia (1939) xxi. 306 You lousy sweatin' old shyster you. 1941 BAKER Dict. Austral. Slang 66 Shyster, a worthless mine. Hence shystering vbl. n. and ppl. a.
1860 Knickerb. Mag. Nov. LVI. 458 (Thornton Amer. Gloss.) A kind of twopenny shystering smartness and snap~judgment smartness. 1872 BRISTED in R. G. White Amer. View Copyright (1880) 40 At Tuesday's session an unprepossessing person..made a ‘shystering’ pettifogging speech. 1895 Weekly Exam. (San Francisco) 19 Sept. 2/6 Those sharp practices generally passing under the name of shystering.
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ADDITIONS SERIES 1993
shyster, n.
Add: shysterism n.
1926 Spectator 12 June 980/2 He is an uncompromising enemy of sham and shysterism in politics. 1981 J. WAINWRIGHT Urge for Justice iii. 168 I'd accepted the brief, knowing that I'd be defending a guilty man. That, of itself, smacked of shysterism.