The corners of brick or stone walls in brick buildings, frequently formed of stones, laid in long and short courses; a wedge used to elevate a mortar or gun to a proper level; in printing, a small wedge used to tighten the pages of type within the chase.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (noun) (n.) (noun)
A wedge.
- The Clarendon dictionary. By William Hand Browne, Samuel Stehman Haldeman. Published 1894. (noun) (n.) (noun)
An instrument to raise anything; a wedge; a small wooden wedge used by printers to fasten the pages of type; the external angle of a wall. See Coin.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (noun) (n.) (noun)
( arch.) A wedge used to support and steady a stone: an external angle, esp. of a building: ( gun.) a wedge of wood or iron put under the breech of heavy guns or the muzzle of siege mortars to raise them to the proper level: ( print.) a wedge used to fasten the types in the forms.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (noun) (n.) (noun)

Usage examples:

From the direction of the wind being at south- east, all vessels going to the north- west harbour, must luff close round the gunner's quoin and haul over for the island, taking care to avoid the reefs with which the shore is lined, and on which the surf breaks with great violence.
- An Historical Journal of the Transactions at Port Jackson and Norfolk Island by John Hunter
There was no hesitation whatever, now; and the first man to come forward was Quoin
- The Ghost Pirates by William Hope Hodgson
" 'e's singin' out for some one to go aft an' relieve ther wheel," said Quoin who had gone to the door to listen.
- The Ghost Pirates by William Hope Hodgson