caul

noun

1. A style of close-fitting circular cap worn by women in the sixteenth century and later, often made of linen.
2. (often capitalized, used on maps) An entry to a mill lead taken from a burn or stream (a mill lead (or mill waterway) is generally smaller than a canal but moves a large volume of water).
3. A membrane.
4. The thin membrane which covers the lower intestines; the omentum.