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For the use of the term shield in tunnel construction, see
tunnelling shield.
A shield is a protective device, meant to intercept attacks. The term often refers to a device that is held
in the hand, as opposed to armour and a bullet proof vest. The oldest form of shield was a protection used to block attacks by hand weapons and arrows. Such shields varied greatly in
construction over time and place, and most civilizations made use of them.
In Europe, shields were used in war up until the 17th century, when gunpowder powered weapons made shields obsolete in the battlefield. Shields for
protection from armed attack is still used by many police forces around the world.
Shields are sometimes used on artillery, as well.
Science fiction works such as Star Trek and Star Wars have popularized the
concept of shields in the form of energy fields used to absorb hostile weapons fire. These shields are often featured on starships, although personal shields have also been described. Such devices are, to date, fictional, but they have
some resemblance to real devices such as magnetic field generators.
In telecommunication, the term shield has the
following meanings:
1. A housing, screen, sheath, or
cover that substantially reduces the coupling of electric, magnetic, or electromagnetic fields into or out of circuits or transmission lines.
2. A protective cover that prevents the accidental contact of objects or persons with parts or components operating at
hazardous voltage levels.
Source: from Federal Standard 1037C and from
MIL-STD-188
In heraldry, the shield is the principal portion of a heraldic
achievement or coat of arms. Figures and patterns are depicted emblazoned
upon the shield in many different arrangements.
Other figures besides the shield are used. Since the shield has been regarded as a war-like device appropriate to men only,
ladies customarily bear their arms upon a lozenge, or diamond-shape, and clergymen bear theirs on a cartouche, or oval.
In physical geography, a shield is a large
Archaean (Precambrian) rock
mass at the centre of a continnent, for example the Canadian Shield
and Baltic Shield. The term in this sense was translated from German
schild by H. B. C. Sollas in Suess's Face of Earth in 1901.
See also
Crest -- Mantling -- Supporters -- Compartment --
Motto
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