CAUL (from O. Eng. calle, Fr. cale, a cap), a close-fitting woman's cap, especially one made of network worn in the 16th and 17th centuries; hence the membranous covering to the heart or brain, the omentum, or the similar covering to the intestines, and particularly, a portion of the amnion, which is sometimes found remaining round the head of a child after birth. To this, called in Scotland "sely how," holy or lucky hood, many superstitions have been attached; it was looked on as a sign of good luck, and when preserved, was kept as a protection against drowning.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)