背骨

背骨	bèi gǔ	spine
背	bēi	variant of 背
背	bēi	to be burdened / to carry on the back or shoulder
背	bèi	the back of a body or object / to turn one's back / to hide something from / to learn by heart / to recite from memory / unlucky (slang) / hard of hearing
骨	gū	used in 骨碌碌 / used in 骨碌
骨	gǔ	bone