SHIELD

v. protect, defend, guard; cover, shelter, screen

n. piece of armor carried on the arm and used to protect the body from missiles and blows; anything used for protection, defense; person who protects, protector; escutcheon

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 or a bullet proof vest.
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S.H.I.E.L.D. (originally an acronym for Supreme Headquarters, International Espionage, Law-Enforcement Division, changed in 1991 to Strategic Hazard Intervention, Espionage and Logistics Directorate) is a fictional counterterrorism and intelligence agency in the Marvel Universe that often deals with superhuman threats. Created by Stan Lee & Jack Kirby, it first appeared in Strange Tales #135 (Aug. 1965).
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Shield any protecting structure. Buller's shield a watch glass fitted over the eye to guard it from infection. [more]Shield - Community and Resources

Noun
1. a protective covering or structure
(hypernym) protective covering, protective cover, protection
(hyponym) nipple shield
(derivation) screen
2. armor carried on the arm to intercept blows
(synonym) buckler
(hypernym) armor, armour
(hyponym) escutcheon, scutcheon
(derivation) screen
Verb
1. protect, hide, or conceal from danger or harm
(synonym) screen
(hypernym) protect
(derivation) buckler
2. hold back a thought or feeling about; "She is harboring a grudge against him"
(synonym) harbor, harbour
(hypernym) hide, conceal

(n.)
To ward off; to keep off or out.
  

(n.)
To cover with, or as with, a shield; to cover from danger; to defend; to protect from assault or injury.
  

(n.)
To avert, as a misfortune; hence, as a supplicatory exclamation, forbid!
  

(n.)
The escutcheon or field on which are placed the bearings in coats of arms. Cf. Lozenge. See Illust. of Escutcheon.
  

(n.)
In lichens, a Hardened cup or disk surrounded by a rim and containing the fructification, or asci.
  

(n.)
Figuratively, one who protects or defends.
  

(n.)
Anything which protects or defends; defense; shelter; protection.
  

(n.)
A spot resembling, or having the form of, a shield.
  

(n.)
A framework used to protect workmen in making an adit under ground, and capable of being pushed along as excavation progresses.
  

(n.)
A coin, the old French crown, or ecu, having on one side the figure of a shield.
  

(n.)
A broad piece of defensive armor, carried on the arm, -- formerly in general use in war, for the protection of the body. See Buckler.