colloq. [f. WHACK(ER + -ING2.] That is a ‘whacker’; abnormally large; ‘thumping,’ ‘whopping.’

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  Often quasi-advb. in whacking big, great.

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1823.  Scott, Quentin D., Introd. 77. A certain whacking priest in our neighbourhood. Ibid. (1829), Jrnl., 16 April (1890), II. 268. This whacking reason.

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1853.  G. J. Cayley, Las Alforjas, II. 193. We saw a whacking great building.

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1873.  C. M. Davies, Unorth. Lond., Walworth Jumpers, 91. A good whacking kiss that echoed all over the archway.

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