Sentence:  Today , according to land economist Homer Hoyt , <WSD>shopping</WSD> centers and their associated parking lots cover some 46000 acres of land , which is almost exactly the total land area in all the nation 's Central Business Districts put together . 
Meaning of the word marked with <WSD> tags:  mercantile establishment consisting of a carefully landscaped complex of shops representing leading merchandisers; usually includes restaurants and a convenient parking area; a modern version of the traditional marketplace