[cleav.age] n (1816) 1 a: the quality of a crystallized substance or rock of splitting along definite planes; also: the occurrence of such splitting b: a fragment (as of a diamond) obtained by splitting
2: the action of cleaving: the state of being cleft
3: the series of synchronized mitotic cell divisions of the fertilized egg that results in the formation of the blastomeres and changes the single-celled zygote into a multicellular embryo; also: one of these cell divisions
4: the splitting of a molecule into simpler molecules
5: the depression between a woman's breasts esp. when made visible by the wearing of a low-cut dress