Definition
A 'fourpenny nail' is a type of nail that's 1 1/2 inches long. The term "penny" (denoted by 'd') refers to the nail's historical price per hundred in England. So, a fourpenny nail would have cost four pennies per hundred nails. It is a historical unit of measure still used today to denote certain nail sizes. The term doesn't reflect the actual current price. It is a common fastener used in woodworking and construction. A fourpenny nail is used for lighter projects.