A quoin is a wedge shaped item used to support or anchor other items.
- In shipping terms it refers to a timber block used to secure barrels against movement. Historically, the same item was used at the breech end of a cannon to raise or lower the weapon's trajectory.
- Quoins in architecture are the corner stones which anchor the edge of the building wall.
- Quoins are also wedges used by printers to hold the hand-set type in place.