Buttocks

The buttocks are two parts of the body. They are on the back of the pelvic area and give padding when people sit. They can also arouse human sexuality.
Buttocks are formed mainly from two large muscles on each side. These are the "gluteus maximus" and the "glutius medius". They go from the hip to the top of the leg, so they are not there just for decoration. The role of the buttocks in sitting and in sexual arousal are secondary functions in our species.
In some African populations the buttocks look bigger because of extra fat. This condition is known as steatopygia. It is an inherited condition first noticed in the Khoisan (San people) of southern Africa and the pygmies of central Africa. Now it has been recognised in the people of the Andamanese islands in the Pacific Ocean.
Slang words for the buttocks include "booty", "butt", "bum", "hiney", and "ass".