COIN - A piece of currency, usually metallic and in the shape of a disc, but sometimes polygonal, or with a hole in the middle.
CORN - A cereal plant grown for its grain, specifically the main such plant grown in a given region, such as oats in parts of Scotland and Ireland, wheat or barley in England and Wales, and maize or sweetcorn in the Americas.
ICON - An image, symbol, picture, or other representation usually as an object of religious devotion.
IRON - A common, inexpensive metal, often black in color, that rusts, is attracted by magnets, and is used in making steel.
IONIC - Of, relating to, or containing ions.
RICIN - A toxic protein extracted from the castor bean.
IRONIC - Characterized by or constituting (any kind of) irony.