[-ING2.] That clacks.

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1611.  Cotgr., Clac … any thing that makes a clacking, or clattering noise.

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1865.  Gosse, Land & Sea (1874), 384. A rushing brook … hurries away to a clacking mill.

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1870.  Morris, Earthly Par., III. 278. The clacking loom … still did stand.

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