Source : Webster's Revised Unabridged Dictionary (1913)

Shield \Shield\, n. [OE. sheld, scheld, AS. scield, scild,
   sceld, scyld; akin to OS. scild, OFries. skeld, D. & G.
   schild, OHG. scilt, Icel. skj["o]ldr, Sw. sk["o]ld, Dan.
   skiold, Goth. skildus; of uncertain origin. Cf. {Sheldrake}.]
   1. A broad piece of defensive armor, carried on the arm, --
      formerly in general use in war, for the protection of the
      body. See {Buckler}.

            Now put your shields before your hearts and fight,
            With hearts more proof than shields.  --Shak.

   2. Anything which protects or defends; defense; shelter;
      protection. ``My council is my shield.'' --Shak.

   3. Figuratively, one who protects or defends.

            Fear not, Abram; I am thy shield, and thy exceeding
            great reward.                         --Gen. xv. 1.

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

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

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

   7. A spot resembling, or having the form of, a shield.
      ``Bespotted as with shields of red and black.'' --Spenser.

   8. A coin, the old French crown, or ['e]cu, 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}.

Source : WordNet®

shield fern
     n : any of various ferns of the genera Dryopteris or Polystichum
         or Lastreopsis having somewhat shield-shaped coverings on
         the sori [syn: {buckler fern}]