Sentence:  Hardly had Mrs. Roebuck driven off when a rusty pick-up truck , father or grandfather of Senor `` Moriarty 's '' Ford sedan , came screeching to a <WSD>dust</WSD> swirling stop , and a brown face appeared , its nose threatened by shards of what had once been the side window . 
Meaning of the word marked with <WSD> tags:  fine powdery material such as dry earth or pollen that can be blown about in the air