The Collaborative International Dictionary of English v.0.48:

Worm \Worm\ (w[^u]rm), n. [OE. worm, wurm, AS. wyrm; akin to D.
   worm, OS. & G. wurm, Icel. ormr, Sw. & Dan. orm, Goth.
   wa['u]rms, L. vermis, Gr. ? a wood worm. Cf. Vermicelli,
   Vermilion, Vermin.]
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   1. A creeping or a crawling animal of any kind or size, as a
      serpent, caterpillar, snail, or the like. [Archaic]
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            There came a viper out of the heat, and leapt on his
            hand. When the men of the country saw the worm hang
            on his hand, they said, This man must needs be a
            murderer.                             --Tyndale
                                                  (Acts xxviii.
                                                  3, 4).
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            'T is slander,
            Whose edge is sharper than the sword, whose tongue
            Outvenoms all the worms of Nile.      --Shak.
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            When Cerberus perceived us, the great worm,
            His mouth he opened and displayed his tusks.
                                                  --Longfellow.
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   2. Any small creeping animal or reptile, either entirely
      without feet, or with very short ones, including a great
      variety of animals; as, an earthworm; the blindworm.
      Specifically: (Zool.)
      (a) Any helminth; an entozoon.
      (b) Any annelid.
      (c) An insect larva.
      (d) pl. Same as Vermes.
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   3. An internal tormentor; something that gnaws or afflicts
      one's mind with remorse.
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            The worm of conscience still begnaw thy soul!
                                                  --Shak.
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   4. A being debased and despised.
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            I am a worm, and no man.              --Ps. xxii. 6.
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   5. Anything spiral, vermiculated, or resembling a worm; as:
      (a) The thread of a screw.
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                The threads of screws, when bigger than can be
                made in screw plates, are called worms. --Moxon.
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      (b) A spiral instrument or screw, often like a double
          corkscrew, used for drawing balls from firearms.
      (c) (Anat.) A certain muscular band in the tongue of some
          animals, as the dog; the lytta. See Lytta.
      (d) The condensing tube of a still, often curved and wound
          to economize space. See Illust. of Still.
      (e) (Mach.) A short revolving screw, the threads of which
          drive, or are driven by, a worm wheel by gearing into
          its teeth or cogs. See Illust. of Worm gearing,
          below.
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   Worm abscess (Med.), an abscess produced by the irritation
      resulting from the lodgment of a worm in some part of the
      body.

   Worm fence. See under Fence.

   Worm gear. (Mach.)
      (a) A worm wheel.
      (b) Worm gearing.

   Worm gearing, gearing consisting of a worm and worm wheel
      working together.

   Worm grass. (Bot.)
      (a) See Pinkroot, 2
      (a) .
      (b) The white stonecrop (Sedum album) reputed to have
          qualities as a vermifuge. --Dr. Prior.

   Worm oil (Med.), an anthelmintic consisting of oil obtained
      from the seeds of Chenopodium anthelminticum.

   Worm powder (Med.), an anthelmintic powder.

   Worm snake. (Zool.) See Thunder snake
      (b), under Thunder.

   Worm tea (Med.), an anthelmintic tea or tisane.

   Worm tincture (Med.), a tincture prepared from dried
      earthworms, oil of tartar, spirit of wine, etc. [Obs.]

   Worm wheel, a cogwheel having teeth formed to fit into the
      spiral spaces of a screw called a worm, so that the wheel
      may be turned by, or may turn, the worm; -- called also
      worm gear, and sometimes tangent wheel. See Illust. of
      Worm gearing, above.
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The Collaborative International Dictionary of English v.0.48:

Fence \Fence\ (f[e^]ns), n. [Abbrev. from defence.]
   1. That which fends off attack or danger; a defense; a
      protection; a cover; security; shield.
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            Let us be backed with God and with the seas,
            Which he hath given for fence impregnable. --Shak.
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            A fence betwixt us and the victor's wrath.
                                                  --Addison.
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   2. An inclosure about a field or other space, or about any
      object; especially, an inclosing structure of wood, iron,
      or other material, intended to prevent intrusion from
      without or straying from within.
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            Leaps o'er the fence with ease into the fold.
                                                  --Milton.
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   Note: In England a hedge, ditch, or wall, as well as a
         structure of boards, palings, or rails, is called a
         fence.
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   3. (Locks) A projection on the bolt, which passes through the
      tumbler gates in locking and unlocking.
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   4. Self-defense by the use of the sword; the art and practice
      of fencing and sword play; hence, skill in debate and
      repartee. See Fencing.
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            Enjoy your dear wit, and gay rhetoric,
            That hath so well been taught her dazzing fence.
                                                  --Milton.
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            Of dauntless courage and consummate skill in fence.
                                                  --Macaulay.
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   5. A receiver of stolen goods, or a place where they are
      received. [Slang] --Mayhew.
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   Fence month (Forest Law), the month in which female deer
      are fawning, when hunting is prohibited. --Bullokar.

   Fence roof, a covering for defense. "They fitted their
      shields close to one another in manner of a fence roof."
      --Holland.

   Fence time, the breeding time of fish or game, when they
      should not be killed.

   Rail fence, a fence made of rails, sometimes supported by
      posts.

   Ring fence, a fence which encircles a large area, or a
      whole estate, within one inclosure.

   Worm fence, a zigzag fence composed of rails crossing one
      another at their ends; -- called also snake fence, or
      Virginia rail fence.

   To be on the fence, to be undecided or uncommitted in
      respect to two opposing parties or policies. [Colloq.]
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WordNet (r) 3.0 (2006):

worm fence
    n 1: rail fence consisting of a zigzag of interlocking rails
         [syn: worm fence, snake fence, snake-rail fence,
         Virginia fence]