Sentence:  However, the sticky <WSD>mousse</WSD> clogged all of the skimmers, even the Vaydaghubsky. If all these skimmers had been on-site during the first three days of calm weather, before the oil was churned into <WSD>mousse</WSD>, they could have made a real difference 
Meaning of the word marked with <WSD> tags:  A stable emulsion of water and oil that is created by wave action churning the water where an oil spill occurs.