Sentence:  One moment , the road was filled with disciplined troops , marching four by four with a purpose as implacable as death ; the next , a <WSD>cloud</WSD> of gun smoke covered a screaming fury of sound , out of which the redcoat soldiers emerged with their bayonets and their cursing fury . 
Meaning of the word marked with <WSD> tags:  any collection of particles (e.g., smoke or dust) or gases that is visible