1 definition by WTDAUSA
When the ass cheeks of a person no longer exist or for that matter curve inward creating a concave surface. Othewise known as a Cass= concave+ass. The opposite of convex.
She had such a flat ass that it had now turned into a Cass.
He had what you would call a Cass, the opposite of a bubble butt.
He had what you would call a Cass, the opposite of a bubble butt.
by WTDAUSA February 4, 2009