High Quality Content by WIKIPEDIA articles! A safe (also called strongbox, coffer or kist) is a secure lockable box used for securing valuable objects against theft or damage. A safe is usually a hollow cuboid or cylinder, with one face removable or hinged to form a door. The body and door may be cast from metal (such as steel) or formed out of plastic through blow molding. A less secure version (only suitable for petty cash) is usually called a cash-box.