cleavage
n//ˈkli.vɪd͡ʒ//klyvning, dekolletage, klyfta, urringning
The act of cleaving or the state of being cleft. [from 19th c.]
The hollow or separation between a woman's breasts, especially as revealed by a low neckline. [from 20th c.]
(by extension) Any similar separation between two body parts, such as the buttocks or toes.