Pileolus

What is a Pileolus? Pileolus is the term for a skull-covering cap worn by high-ranking Christian clergy. This religious headgear is worn by abbots, bishops, cardinals, and the pope either visibly with the soutane garment or under other religious head coverings such as the Mitre.

The colour indicates the rank and function of the wearer, as white is reserved for the pope, while scarlet red signifies cardinals and violet is associated with bishops. Abbots wear a Pileolus in the colours of their religious clothing, and all other clergy and monks are allowed to wear a black skull cap.

Another characteristic is the material; while the pope and cardinals typically wear a Pileolus made of Moiré velvet, the headgear of other dignitaries is made of simple silk. The Pileolus (Latin pileus = hat/cap) is occasionally also called Zucchetto (Italian = small pumpkin) or Soli Deo (Latin = only before God). Presumably, the skull cap originated from a somewhat larger religious head covering from the Middle Ages, which still covered the ears and temples. Over time, it has become much smaller, covering only the monk's typical tonsure, i.e., the traditionally shaved crown with a remaining hair wreath. Apart from the religious use and appearance, there is no connection to the uniform Kippah of the Jews.