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

cleavage \cleav"age\, n.
   1. the act of cleaving or splitting.
      1913 webster

   2. crystallog. the quality possessed by many crystallized
      substances of splitting readily in one or more definite
      directions, in which the cohesive attraction is a minimum,
      affording more or less smooth surfaces; the direction of
      the dividing plane; a fragment obtained by cleaving, as of
      a diamond. see parting.
      1913 webster

   3. geol. division into laminae, like slate, with the
      lamination not necessarily parallel to the plane of
      deposition; -- usually produced by pressure.
      1913 webster

   basal cleavage, cleavage parallel to the base of a crystal,
      or to the plane of the lateral axes.

   cell cleavage biol., multiplication of cells by fission.
      see segmentation.

   cubic cleavage, cleavage parallel to the faces of a cube.
      

   diagonal cleavage, cleavage parallel to ta diagonal plane.
      

   egg clavage. biol. see segmentation.

   lateral cleavage, cleavage parallel to the lateral planes.
      

   octahedral cleavage, dodecahedral cleavage, or
   rhombohedral cleavage, cleavage parallel to the faces of an
      octahedron, dodecahedron, or rhombohedron.

   prismatic cleavage, cleavage parallel to a vertical prism.
      1913 webster
see also:
parting basal cleavage cell cleavage segmentation cubic cleavage diagonal cleavage 
egg clavage lateral cleavage octahedral cleavage dodecahedral cleavage rhombohedral cleavage 
prismatic cleavage 

Prismatic >> P Words
Prismatic, definition of term: Prismatic
prismatic_pag1.html

Cleavage >> C Words
Cleavage, definition of term: Cleavage
cleavage_pag1.html