CLEAVAGE

noun the act of cleaving or splitting.

2. cleavage ·noun division into laminae, like slate, with the lamination not necessarily parallel to the plane of deposition;

— usually produced by pressure.

3. cleavage ·noun 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.