Cleavage

In embryology, the term cleavage refers to the cell divisions of the early embryo.

In mineralogy, the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types:

• Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes.

• Cubic cleavage: cleavage parallel to the faces of a cube.

• Diagonal cleavage: cleavage parallel to a diagonal plane.

• Lateral cleavage: cleavage parallel to the lateral planes.

• Octahedral, Dodecahedral, or Rhombohedral cleavage: cleavage parallel to the faces of an octahedron, dodecahedron, or rhombohedron.

• Prismatic cleavage, cleavage parallel to a vertical Prism.

Also the separation between a woman's breasts, or any line formed by a groove between two parts.