mill-stone

Noun

millstone (plural millstones)

1. A large round stone used for grinding grain.
   • As it is the circular Motion of the Mill-ſtone which brings the Corn out of the Hopper by Jerks, and with a Velocity depending upon that of the Stone, other Grains are always ſucceeding, which raiſe it anew, and the Flower just made being no longer preſs'd is carry'd away into the Boulting Mill by...1744, J[ohn] T[heophilus] Desaguliers, “Lecture XII. On Engines, especially Hydrostatical and Hydraulick Machines.”, in A Course of Experimental Philosophy, volume II, London: Printed for W. Innys...
2. A coarse-grained sandstone used for making such stones; millstone grit.
   • In North America the millstone grit, and a grey sandy and slaty rock beneath it, occur three times; and it is exceedingly difficult to distinguish these rocks in hand specimens, without the aid of organized remains. And remains are almost exclusively confined to the grey rocks. Common quarrymen...1832, Amos Eaton, Geological Text-book, for Aiding the Study of North American Geology: Being a Systematic Arrangement of Facts, Collected by the Author and His Pupils, under the Patronage of the...

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