Merriam-Webster Collegiate Dictionary - escutcheon

 noun  Etymology: Middle English escochon, from Anglo-French escuchoun, from Vulgar Latin *scution-, scutio, from Latin scutum shield — more at esquire  Date: 15th century  1. a defined area on which armorial bearings are displayed and which usually consists of a shield  2. a protective or ornamental plate or flange (as around a keyhole)  3. the part of a ship's stern on which the name is displayed