Cleavage
From wipipedia.org
File:Exposed backside cleavage.jpg
Rear cleavage
Cleavage literally means the gap between a woman's breasts. It is generally used to mean the sight of this gap, or of the breasts themselves, as revealed by a low-cut garment.
Perhaps not surprisingly, most fetish fashion designers design many of their women's garments to emphasise the wearer's cleavage.
The term is also used to describe a glimpse of the top of the buttocks (of a man or woman) over low-cut trousers; this is also called rear cleavage.
