Source : Webster's Revised Unabridged Dictionary (1913)

Fence \Fence\, v. t. [imp. & p. p. Fenced (?); p. pr. & vb. n.
   {Fencing}.]
   1. To fend off danger from; to give security to; to protect;
      to guard.

            To fence my ear against thy sorceries. --Milton.

   2. To inclose with a fence or other protection; to secure by
      an inclosure.

            O thou wall! . . . dive in the earth, And fence not
            Athens.                               --Shak.

            A sheepcote fenced about with olive trees. --Shak.

   {To fence the tables} (Scot. Church), to make a solemn
      address to those who present themselves to commune at the
      Lord's supper, on the feelings appropriate to the service,
      in order to hinder, so far as possible, those who are
      unworthy from approaching the table. --McCheyne.

Fence \Fence\, n. [Abbrev. from defence.]
   1. That which fends off attack or danger; a defense; a
      protection; a cover; security; shield.

            Let us be backed with God and with the seas, Which
            he hath given for fence impregnable.  --Shak.

            A fence betwixt us and the victor's wrath.
                                                  --Addison.

   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.

            Leaps o'er the fence with ease into the fold.
                                                  --Milton.

   Note: In England a hedge, ditch, or wall, as well as a
         structure of boards, palings, or rails, is called a
         fence.

   3. (Locks) A projection on the bolt, which passes through the
      tumbler gates in locking and unlocking.

   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}.

            Enjoy your dear wit, and gay rhetoric, That hath so
            well been taught her dazzing fence.   --Milton.

            Of dauntless courage and consummate skill in fence.
                                                  --Macaulay.

   5. A receiver of stolen goods, or a place where they are
      received. [Slang] --Mayhew.

   {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.]

Fence \Fence\, v. i.
   1. To make a defense; to guard one's self of anything, as
      against an attack; to give protection or security, as by a
      fence.

            Vice is the more stubborn as well as the more
            dangerous evil, and therefore, in the first place,
            to be fenced against.                 --Locke.

   2. To practice the art of attack and defense with the sword
      or with the foil, esp. with the smallsword, using the
      point only.

            He will fence with his own shadow.    --Shak.

   3. Hence, to fight or dispute in the manner of fencers, that
      is, by thrusting, guarding, parrying, etc.

            They fence and push, and, pushing, loudly roar;
            Their dewlaps and their sides are bat?ed in gore.
                                                  --Dryden.

            As when a billow, blown against, Falls back, the
            voice with which I fenced A little ceased, but
            recommenced.                          --Tennyson.

Source : WordNet®

fence
     v 1: enclose with a fence; "we fenced in our yard" [syn: {fence
          in}]
     2: receive stolen goods
     3: fight with fencing swords
     4: surround with a wall in order to fortify [syn: {wall}, {palisade},
         {fence in}, {surround}]
     5: have an argument about something [syn: {argue}, {contend}, {debate}]

fence
     n 1: a barrier that serves to enclose an area [syn: {fencing}]
     2: a dealer in stolen property

Source : Free On-Line Dictionary of Computing

fence
     
        1. A sequence of one or more distinguished ({out-of-band})
        characters (or other data items), used to delimit a piece of
        data intended to be treated as a unit (the computer-science
        literature calls this a "sentinel").  The NUL (ASCII 0000000)
        character that terminates strings in C is a fence.  {Hex} FF
        is also (though slightly less frequently) used this way.  See
        {zigamorph}.
     
        2. An extra data value inserted in an array or other data
        structure in order to allow some normal test on the array's
        contents also to function as a termination test.  For example,
        a highly optimised routine for finding a value in an array
        might artificially place a copy of the value to be searched
        for after the last slot of the array, thus allowing the main
        search loop to search for the value without having to check at
        each pass whether the end of the array had been reached.
     
        3. [among users of optimising compilers] Any technique,
        usually exploiting knowledge about the compiler, that blocks
        certain optimisations.  Used when explicit mechanisms are not
        available or are overkill.  Typically a hack: "I call a dummy
        procedure there to force a flush of the optimiser's
        register-colouring info" can be expressed by the shorter
        "That's a fence procedure".
     
        [{Jargon File}]
     
        (1999-01-08)