quoin

The order to adjust the quoin in great-gun exercise; to depress the muzzle to point at an object below the level, in contradistinction to elevate.

From The Sailor's Word-Book An Alphabetical Digest of Nautical Terms, including Some More Especially Military and Scientific, but Useful to Seamen; as well as Archaisms of Early Voyagers, etc. by Sir Edward Belcher

He fell on his knees, with his face on his hands in the open quoin drawer, feeling as if he had uttered a blasphemy.

From Despair's Last Journey by David Christie Murray

The larger one is quoin shaped, and has a remarkable perforation, seen in the sketch.

From The Mirror of Literature, Amusement, and Instruction Volume 19, No. 537, March 10, 1832 by Various

So that below the girdle, we find twenty-five facets: 8 cross, 8 skill, 4 pavilion, 4 quoin, and 1 collet.

From The Chemistry, Properties and Tests of Precious Stones by John Mastin

"Knock away the quoin, entirely;" he said to the captain of the gun, when he had got the range; "now mind her when she lifts, forward; keep the ship steady, Sir—fire!"

From The Water-Witch or, the Skimmer of the Seas by James Fenimore Cooper