MILLSTONES

Noun

millstones

plural of millstone.

Source: Wiktionary

MILLSTONE

Mill"stone`, n.

Definition: One of two circular stones used for grinding grain or other substance. No man shall take the nether or the upper millstone to pledge. Deut. xxiv. 6.

Note: The cellular siliceous rock called buhrstone is usually employed for millstones; also, some kinds of lava, as that Niedermendig, or other firm rock with rough texture. The surface of a millstone has usually a series of radial grooves in which the powdered material collects. Millstone girt (Geol.), a hard and coarse, gritty sandstone, dividing the Carboniferous from the Subcarboniferous strata. See Farewell rock, under Farewell, a., and Chart of Geology.

– To see into, or through, a millstone, to see into or through a difficult matter. (Colloq.)

Source: Webster’s Unabridged Dictionary 1913 Edition