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Webster 1913 Edition

Noun.

Cloth made waterproof by oil.

Icelandic fisherman dressed in oilskin.

See also: oilskins

oilskin ‎(uncountable)

Cloth made from cotton and treated with oil and pigment to make it waterproof.
A raincoat made from cotton fabric treated with oil and pigment to make it waterproof.
(by extension) Foul-weather gear worn by sailors, whether of natural or synthetic materials.

cloth made from cotton treated to make it waterproof

raincoat made from treated cotton fabric

foul-weather gear worn by sailors