Source : Webster's Revised Unabridged Dictionary (1913)

Plumb \Plumb\, v. t. [imp. & p. p. {Plumbed}; p. pr. & vb. n.
   {Plumbing}.]
   1. To adjust by a plumb line; to cause to be perpendicular;
      as, to plumb a building or a wall.

   2. To sound with a plumb or plummet, as the depth of water;
      hence, to examine by test; to ascertain the depth,
      quality, dimension, etc.; to sound; to fathom; to test.

            He did not attempt to plumb his intellect. --Ld.
                                                  Lytton.

   3. To seal with lead; as, to plumb a drainpipe.

   4. To supply, as a building, with a system of plumbing.

Plumbing \Plumb"ing\, n.
   1. The art of casting and working in lead, and applying it to
      building purposes; especially, the business of furnishing,
      fitting, and repairing pipes for conducting water, sewage,
      etc. --Gwilt.

   2. The lead or iron pipes, and other apparatus, used in
      conveying water, sewage, etc., in a building.

Source : WordNet®

plumbing
     n 1: utility consisting of the pipes and fixtures for the
          distribution of water or gas in a building and for the
          disposal of sewage [syn: {plumbing system}]
     2: the occupation of a plumber (installing and repairing pipes
        and fixtures for water or gas or sewage in a building)
        [syn: {plumbery}]
     3: measuring the depths of the oceans [syn: {bathymetry}]

Source : Free On-Line Dictionary of Computing

plumbing
     
        (Unix) Term used for {shell} code, so called because of the
        prevalence of "{pipeline}s" that feed the output of one
        program to the input of another.  Under {Unix}, user utilities
        can often be implemented or at least prototyped by a suitable
        collection of pipelines and temporary file {grind}ing
        encapsulated in a {shell script}.  This is much less effort
        than writing {C} every time, and the capability is considered
        one of Unix's major winning features.  A few other {operating
        system}s such as {IBM}'s {VM/CMS} support similar facilities.
     
        The {tee} utility is specifically designed for plumbing.
     
        [{Jargon File}]
     
        (1995-02-23)