A recent television commercial refers to Keister, a Minnesota town, having a population of about 500 people.  A woman on a bicycle rides around the town, coasting by a market, a fire department, and a marching band, referring to the town name each scene.  Then, while sitting on that hard bike seat, she refers to her own “keister,” remarking:  “And if I can get comfortable talking about this Keister, then you can get comfortable using Preparation H.” — an ointment to relieve the pain and itching caused by hemorrhoids.   

Every television viewer would have associated “Keister” immediately as a slang word for Gluteus Maximus or buttocks, the correct anatomical words for one’s posterior.  Actually, many other dictionary words exist to differentiate one bum from another.  Some viable candidates:  

Rump, 

Tush, 

Tooshie, 

Ass (vulgar), 

Bum, 

Bottom, 

Behind, 

Butt

Derriere,

Keister,

Fanny, 

Duff, 

Hiny (heinie), 

Booty

Other terms exist, of course, so the above list is not intended to be an end-all.   At bottom, Ancient Greece concocted some interesting distinguishing terms to differentiate various rump characteristics, thus demonstrating that Derriere watching is older than the Acropolis. Some examples: 

Callipygian (kal-uh-PIJ-ee-uhn):  having a shapely (well-proportioned and pleasing shape) buttocks.  Its origin comes from the Greek, referring to a statue of  Aphrodite, as beautiful (calli) + pyge (rump.)  What would one call a terrible shaped buttocks?  

Cacopygian (ka co PIJ ee-uhn), Having an ugly buttocks.  as the “caco” root is the opposite of “calli.” 

Dasypygian (da see PIJ ee-un)  Having a hairy buttocks.

Steatopygian (Ste-at-o-PIJ-ee-uhn:)  Having an accumulation of large amounts of fat on the buttocks; ie, a fat rump.  The build is not confined to the “gluteal” regions, but extends to the outside and front of the thighs and tapers to the knee.  (Steatopygia, wikipedia.com)  

I could go on — butt, I must bring this post to an end.