oilskin          
noun uk/ˈɔɪl.skɪn/ us/ˈɔɪl.skɪn/
 [ U ]防水油布,防雨油布 
cotton cloth that has a thin layer of oil on it to make it waterproof
  a hat made of oilskin 防雨油布做的帽子 
  [ C usually plural ](油布)雨衣 
a piece of clothing made out of oilskin
  The fishermen were all wearing oilskins. 渔民们都穿着油布雨衣。