When the breasts rest far apart, either due to gravity pulling them apart or due to being physically held apart.
As a rule of thumb, the breasts should point away from each other and the skin over the breastbone should be visible.
The opposite of cleavage. Not for when the breasts don't touch because of a natural gap, or when they're too small to touch, or when they don't touch because something between breasts.
This tag implicates