空心墙

空心墙	kōng xīn qiáng	cavity wall / hollow wall
空	kōng	empty / air / sky / in vain
空	kòng	to empty / vacant / unoccupied / space / leisure / free time
空心	kōng xīn	hollow / (of vegetables) to become hollow or spongy inside / (of a basketball) to swish through (not touching the hoop)
空心	kòng xīn	on an empty stomach
心	xīn	heart / mind / intention / center / core / CL:颗,个
墙	qiáng	variant of 墙
墙	qiáng	wall (CL:面,堵) / (slang) to block (a website) (usu. in the passive: 被墙)