Noun

1. A broad piece of defensive armor, carried on the arm, formerly in general use in war, for the protection of the body.

   • 1599: Knocks go and come; God's vassals drop and die; And sword and shield, In bloody field, Doth win immortal fame. — William Shakespeare, Henry V, Act III, Scene II, line 8.
   • 1786: The shields used by our Norman ancestors were the triangular or heater shield, the target or buckler, the roundel or rondache, and the pavais, pavache, or tallevas. — Francis Grose, A Treatise on Ancient Armour and Weapons, page 22.

2. Anything which protects or defends; defense; shelter; protection.

   • 1592: Go muster men. My counsel is my shield; We must be brief when traitors brave the field. — William Shakespeare, Richard III, Act 4, Scene 3, line 56.

3. Figuratively, one who protects or defends.

   • 1611: Fear not, Abram: I am thy shield, and thy exceeding great reward. The Holy Bible, King James Version, Genesis 15:1.

4. In lichens, a hardened cup or disk surrounded by a rim and containing the fructification, or asci.
5. The escutcheon or field on which are placed the bearings in coats of arms.
6. A large expanse of exposed stable Precambrian rock.
7. A framework used to protect workmen in making an adit under ground, and capable of being pushed along as excavation progresses.
8. A spot resembling, or having the form of a shield.

   Bespotted as with shields of red and black. Spenser.

9. A coin, the old French crown, or écu, having on one side the figure of a shield.
10. A field of energy which protects or defends.
11. A police badge

    • The chief put something in his hand and Bosch looked down to see the gold detective's shield. http://www.michaelconnelly.com/Book_Collection/Closers/ClosersExcerpt/closersexcerpt.html

12. A sign or symbol, usually containing numbers and sometimes letters, identifying a highway route.

Hyponyms

• Shield (1) types: buckler, pavache, pavais, rondache, roundel, tallevas, targe, and target.

Verb

1. To protect, to defend.
   • 2004: Chris Wallace, Character: Profiles in Presidential Courage

     Shots rang out and a 15-year-old boy, shielding a woman from the line of fire, was killed.

2. to protect from the influence of