Sentence:  Half crazed by the weight dragging , the dust , and the heat , the horse leaped our <WSD>wall</WSD> , dashing out the rider 's brains against it , and leaving him lying there among us - while the horse crashed away through the brush . 
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