What does "shield" mean?

Additional senses

1. 2.Figuratively, one who protects or defends. Fear not, Abram; I am thy shield, and thy exceeding great reward. Gen. xv.
2. 3.4. (Bot.) In lichens, a Hardened cup or disk surrounded by a rim and containing the fructification, or asci.
3. 4.(Her.) The escutcheon or field on which are placed the bearings in coats of arms. Cf. Lozenge. See Illust. of Escutcheon.
4. 5.(Mining & Tunneling) A framework used to protect workmen in making an adit under ground, and capable of being pushed along as excavation progresses.
5. 6.A spot resembling, or having the form of, a shield. "Bespotted as with shields of red and black." Spenser.
6. 7.A coin, the old French crown, or écu, having on one side the figure of a shield. [Obs.] Chaucer. Shield fern (Bot.), any fern of the genus Aspidium, in which the fructifications are covered with shield-shaped indusia; -- called also wood fern. See Illust. of Indusium.
7. 8.To cover with, or as with, a shield; to cover from danger; to defend; to protect from assault or injury. Shouts of applause ran ringing through the field, To see the son the vanquished father shield. Dryden. A woman's shape doth shield thee. Shak.
8. 9.To ward off; to keep off or out. They brought with them their usual weeds, fit to shield the cold to which they had been inured. Spenser.
9. 10.To avert, as a misfortune; hence, as a supplicatory exclamation, forbid! [Obs.] God shield that it should so befall. Chaucer. God shield I should disturb devotion! Shak.