As you head east down the Thames the river is lined with old warehouses; these days they are almost exclusively given over to restaurants and luxury apartments, but once they were the heart on London’s roaring river trade. If you look ‘wharf’ up in the dictionary it’ll give the formal origins of the word, but if you go on one of the tourist boats that ply the river these days they’ll tell you it’s a shortened version ‘warehouse at river front’. I prefer their version!