adj. and adv. (GROSE).—‘Under the rose; transacting business privately is frequently said to be done UPON THE SLY’; illicit: also BY THE SLY; TO RUN SLY = to escape, to evade.

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  c. 1787.  Kilmainham Minit [Ireland Sixty Years Ago, 88].

        But if dat de slang you RUN SLY,
  De scrag-boy may yet be outwitted,
    And I scout again on de lay.

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  1851–61.  H. MAYHEW, London Labour and the London Poor, I. 318. A SLY trade’s always the best for paying, and for selling too.

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  1872.  G. ELIOT, Middlemarch, lxxviii. Selling myself for any devil’s change BY THE SLY.

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  1887.  W. E. HENLEY, Culture in the Slums. I keeps a Dado ON THE SLY.

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