<p><strong>Noun</strong></p><ul><li>a broad piece of armor, varying widely in form and size, carried apart from the body, usually on the left arm, as a defense against swords, lances, arrows, etc.</li><li>a similar device, often of lightweight plastic, used by riot police to protect themselves from rocks and other thrown objects.</li><li>something shaped like a shield, variously round, octagonal, triangular, or somewhat heart-shaped.</li><li>a person or thing that protects.</li><li>a police officer's, detective's, or sheriff's badge.</li><li>Ordnance: a steel screen attached to a gun to protect its crew, mechanism, etc.</li><li>Mining: a movable framework for protecting a miner from cave-ins, etc.</li><li>Electricity: a covering, usually made of metal, placed around an electric device or circuit in order to reduce the effects of external electric and magnetic fields.</li><li>Zoology: a protective plate or the like on the body of an animal, as a scute, enlarged scale, etc.</li><li>dress shield.</li><li>Heraldry: an escutcheon, especially one broad at the top and pointed at the bottom, for displaying armorial bearings.</li><li>Shield, Astronomy: the constellation Scutum.</li><li>Geology: a vast area of ancient crustal rocks which, together with a platform, constitutes a craton.</li><li>a protective barrier against nuclear radiation, especially a lead or concrete structure around a reactor.</li></ul><p><strong>Verb</strong></p><ul><li>to protect (someone or something) with or as if with a shield.</li><li>to serve as a protection for.</li><li>to hide or conceal; protect by hiding.</li><li>Obsolete: to avert; forbid.</li></ul><p><strong>Verb (used without object)</strong></p><ul><li>to act or serve as a shield.</li></ul>