1 definition by WTDAUSA

Top Definition
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.
by WTDAUSA February 04, 2009
Free Daily Email

Type your email address below to get our free Urban Word of the Day every morning!

Emails are sent from daily@urbandictionary.com. We'll never spam you.