Толковый словарь английского языка - cleavage

noun Date: 1816 1. the quality of a crystallized substance or rock of splitting along definite planes, a fragment (as of a diamond) obtained by splitting, the action of cleaving ; the state of being cleft, the series of synchronized mitotic cell divisions of a fertilized egg that results in the formation of the blastomeres and changes the single-celled zygote into a multicellular embryo, the splitting of a molecule into simpler molecules, the depression between a woman's breasts especially when made visible by a low-cut neckline