the.com/oilskin

means A fabric treated with oil (or, later, a garment made from it) to make it waterproof, traditionally worn by sailors and fishermen braving wet weather.

from From 'oil' + 'skin' — fabric, often cotton or linen, was soaked or coated with oil (originally linseed oil) to seal its fibers against water. The process dates back centuries, long before synthetic waterproofing existed, and 'skin' here points to the way the oiled cloth formed a protective outer layer, much like an animal hide. The term stuck even as materials and treatments evolved, carried along by the maritime trades that depended on it most.