Sentence:  At once my ears were drowned by a flow of what I took to be Spanish , but - the <WSD>driver</WSD> 's white teeth flashing at me , the road wildly veering beyond his glistening hair , beyond his gesticulating bottle - it could have been the purest Oxford English I was half hearing ; I would n't have known the difference . 
Meaning of the word marked with <WSD> tags:  the operator of a motor vehicle