thass; the area in which your ass and thigh join as one. there should be definition between the two, a thigh... then your ass, creating a "shelf" if you will. but when you start to gain weight you loose that definition, thus creating the infamous thass.
*cousin to the kankle

"Look at the thass on that!"

thass by Miss White of the WFSU crew AKA Karena July 18, 2006

thass

Thass; the thigh / ass crease or more importantly the lack there of.

Her ass has become one with her thigh , where there was once once a seperation there is no more.

thass by Jesse May 13, 2005

Thass

where ones ass and thigh look like its merged together

Look at the thass on him, he shouldn't wear football pants.

Thass by ilovemanning10 October 26, 2008

Thass

That small area on either a male or females body,that is right between one's ass and one's upper thigh,could be the crease or just that area that on some people just blends together.

Oh that hurts, a spider just crawled up my leg and bit me on the thass!

Thass by 4you May 7, 2009

Thass

The are area of the body between your ass cheek and your thigh....

Thass nice.

Thass by TIVA January 25, 2016