caul:
caul /kôl/ I. noun 1. the amniotic membrane enclosing a fetus. 2. part of the amniotic membrane occasionally found on a child's head at birth, thought to bring good luck. 3. ‹historical› a woman's close-fitting indoor headdress or hairnet. 4. [Anatomy] the omentum. – origin Middle English: perhaps from Old French cale ‘head covering,’ but recorded earlier.
