caul

noun

1. 1.A style of close-fitting circular cap worn by women in the sixteenth century and later, often made of linen.
2. 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. 3.A membrane.
4. 4.The thin membrane which covers the lower intestines; the omentum.
5. 5.The amnion which encloses the foetus before birth, especially that part of it which sometimes shrouds a baby’s head at birth (traditionally considered to be good luck).