[1] : The Collaborative International Dictionary of English v.0.48

caliber \cal"iber\, calibre \cal"ibre\, n. f. calibre, perh.
   fr. l. qualibra of what pound, of what weight; hence, of what
   size, applied first to a ball or bullet; cf. also ar.
   q=alib model, mold. cf. calipers, calivere.
   1913 webster
   1. gunnery the diameter of the bore, as a cannon or other
      firearm, or of any tube; or the weight or size of the
      projectile which a firearm will carry; as, an 8 inch gun,
      a 12-pounder, a 44 caliber.
      1913 webster

            the caliber of empty tubes.           --reid.
      1913 webster

            a battery composed of three guns of small caliber.
                                                  --prescott.
      1913 webster

   note: the caliber of firearms is expressed in various ways.
         cannon are often designated by the weight of a solid
         spherical shot that will fit the bore; as, a
         12-pounder; pieces of ordnance that project shell or
         hollow shot are designated by the diameter of their
         bore; as, a 12 inch mortar or a 14 inch shell gun;
         small arms are designated by hundredths of an inch
         expressed decimally; as, a rifle of .44 inch caliber.
         1913 webster

   2. the diameter of round or cylindrical body, as of a bullet
      or column.
      1913 webster

   3. fig.: capacity or compass of mind. --burke.
      1913 webster

   caliber compasses. see calipers.

   caliber rule, a gunner's calipers, an instrument having two
      scales arranged to determine a ball's weight from its
      diameter, and conversely.

   a ship's caliber, the weight of her armament.
      1913 webster
see also:
calipers calivere caliber compasses caliber rule a ship's caliber 

[2] : WordNet (r) 2.0

calibre
     n 1: a degree or grade of excellence or worth; "the quality of
          students has risen"; "an executive of low caliber" syn:
           quality, caliber
     2: diameter of a tube or gun barrel syn: bore, gauge, caliber
see also:
quality caliber bore gauge 

Calibre >> C Words
Calibre, definition of term: Calibre
calibre_pag1.html