A cap worn by the flamines and salii at Rome. The essential part of the apex, to which alone the name properly belonged, was a pointed piece of olive-wood, the base of which was surrounded with a lock of wool. This was worn on the top of the head, and was held there either by fillets only, or, as was more commonly the case, by the aid of a cap which fitted the head, and was also fastened by means of two strings or bands. - Smith, 1873