Cleaval Tautness 

The section of a woman's shirt in between the breasts that is stretched horizontally by her breasts and/or cleavage. Visually, the stretched shirt material is seen to have ripples that signify the mechanical pressure that the (usually large) breasts exert on their restraints.

Did you see Madison yesterday? Her shirt had significant cleaval tautness due to her massive rack.

Cleaval Tautness by Fetus Keepus March 16, 2022