Sentence:  Not only were the platforms tiled in <WSD>white</WSD>, the tunnels were painted <WSD>white</WSD> too - to prettify them, and make them less claustrophobic - and the Central proudly issued a postcard of its tunnel-whitening machine. 
Meaning of the word marked with <WSD> tags:  The color/colour of snow or milk; the colour of light containing equal amounts of all visible wavelengths.