COIF (from Fr. coiffe, Ital. cuffia, a cap)  , a close-fitting covering for the head . Originally it was the name given to a head-covering worn in the middle ages, tied like a night-cap under the chin, and worn out of doors by both sexes; this was later worn by men as a kind of night-cap or skull-cap . The coif was also a close-fitting cap of white lawn or silk, worn by English serjeantsat-law as a distinguishing mark of their profession . It became the fashion to wear on the top of the white coif a small skull-cap of black silk or velvet; and on the introduction of wigs at the end of the 17th century a round space was left on the top of the wig for the display of the coif, which was afterwards covered by a small patch of black silk edged with white (see A . Pulling, Order of the Coif, 1897) . The random conjecture of Sir H . Spelman (Glossarium archaiologicum) that the coif was originally designed to conceal the ecclesiastical tonsure has unfortunately been quoted by annotators of Blackstone's Commentaries as well as by Lord Campbell in his Lives of the Chief Justices . It may be classed with the curious conceit, recorded in Brand's Popular Antiquities, that the coif was derived from the child's caul, and was worn on the advocate's head for luck .