Sentence:  And the bed that sagged in a certain place where all the weight had been put too many times before and the walls fine and thin for overhearing talk in the next room when Gratt went out for ice , the sound coming through the <WSD>walls</WSD> like something on the other side of the curtain , so you knew they heard you when they were quiet and while you lay wondering what they had heard you listened . 
Meaning of the word marked with <WSD> tags:  an architectural partition with a height and length greater than its thickness; used to divide or enclose an area or to support another structure