Hip, 臀部，either side of the body below the waist and above the thigh;the ball-and-socket joint between the head of the femur and the acetabulum
Ass, 屁股，slang for sexual intercourse
haunch，臀部，the loin and leg of a quadruped;the hip and buttock and upper thigh in human beings
buttock，臀部，either of the two large fleshy masses of muscular tissue that form the human rump
所以，从以上英文意义可以看出来，ass，是一个与性相关的俚语，意思是爱谁谁????
buttock，是指屁股那两块肉
hip，是指腰以下腿骨以上的那个区域
haunch，是指大腿上部包括hip和buttock的整个大屁股
如果以美国来打比方，ass好比美国佬，hip好比墨西哥以上加拿大以下的区域，buttock是我们通常讲的美国，haunch好比全美，包括阿拉斯加。
