Source : Webster's Revised Unabridged Dictionary (1913)

Packing \Pack"ing\, n.
   1. The act or process of one who packs.

   2. Any material used to pack, fill up, or make close.
      Specifically (Mach.): A substance or piece used to make a
      joint impervious; as:
      (a) A thin layer, or sheet, of yielding or elastic
          material inserted between the surfaces of a flange
          joint.
      (b) The substance in a stuffing box, through which a
          piston rod slides.
      (c) A yielding ring, as of metal, which surrounds a piston
          and maintains a tight fit, as inside a cylinder, etc.

   3. (Masonry) Same as {Filling}. [Rare in the U. S.]

   4. A trick; collusion. [Obs.] --Bale.

   {Cherd packing} (Bridge Building), the arrangement, side by
      side, of several parts, as bars, diagonals, a post, etc.,
      on a pin at the bottom of a chord. --Waddell.

   {Packing box}, a stuffing box. See under {Stuffing}.

   {Packing press}, a powerful press for baling cotton, wool,
      hay, etc.

   {Packing ring}. See {Packing}, 2
      (c), and Illust. of {Piston}.

   {Packing sheet}.
      (a) A large cloth for packing goods.
      (b) A sheet prepared for packing hydropathic patients.

Source : WordNet®

packing box
     n 1: a small chamber in which packing is compressed around a
          reciprocating shaft or piston to form a seal [syn: {stuffing
          box}]
     2: a large crate in which goods are packed for shipment or
        storage [syn: {packing case}]