verb. (common).—To flog; to strike with a birch. Hence BIRCH-OIL = a thrashing: cf., STRAP OIL, HAZEL-OIL, etc.

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  183[?].  HOOD, Ode Clapham Acad.

        There I was BIRCH’d, there I was bred.
There like a little Adam fed
    From Learning’s woeful tree!

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  CLEAN BIRCH, subs. (old).—a pretended conjuror.

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  1772.  BRIDGES, A Burlesque Translation of Homer, 180.

                  So this CLEAN BIRCH
Was by the devil left i’ th’ lurch.

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