Sentence:  Hardly had Mrs. Roebuck driven off when a rusty pick-up truck , father or <WSD>grandfather</WSD> of Senor `` Moriarty 's '' Ford sedan , came screeching to a dust 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:  the father of your father or mother