The intermammary cleft, also known as the cleavage or decolletage, is the area between a woman's breasts. There are several synonyms for this term, including intermammary sulcus, inframammary cleft, and intermammary sulci. Other slang terms for this area include boob gap, tit valley, and cleave. While these terms may be less formal, they are commonly used in pop culture and slang language. However, it's important to remember to use respectful and appropriate language when referring to a person's body, especially in professional or medical settings.