buttocks; thigh

strokes 17
strokes after radical 8
搏髀 搏髀 bo2 bi4
to beat time by slapping one's thighs

拊髀 拊髀 fu3 bi4
to slap one's own buttocks in excitement or despair

周髀算经 周髀算經 zhou1 bi4 suan4 jing1
Zhou Bi Suan Jing, or Chou Pei Suan Ching, one of the oldest Chinese texts on astronomy and mathematics