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2.
A condition in which a woman has a normally proportioned body except her extremely large butt. It is frequent occurance in Massachusetts.
At first I found the cashier quite attractive, until she stepped out from behind the counter and I saw her mass ass.
by Scottus April 29, 2005
 
1.
1. a severe condition in which a woman's ass is out of proportion with the rest of the body.

2. a ass so big, even thinking about it will get you lost.

3. a ass so gargantuan, the only thing that gives definition is it's cellulite

4. Booty for days or ass for days--Ebonics
Rhinocop-I hooked up w/ Heavy D last night
Ian-What did you do?
Rhinocop-Yea i tapped that...
Ian-...You mean you got tapped by the mass ass
Rhinocop-Yea!
Ian-Your sick!