Tonsure is the hairstyle associated with Catholic monks. It derives from the Latin word “tondere” meaning “to shear.” Its origins are unclear. In the Medieval Church it became the rite performed when a monk entered into a sacred order. Novices had their hair cut short upon entering a monastery. Once the monk took their vows, the hair was shaved at the top of the crown.
Other styles competed with Peterine (Roman tonsure). Celtic tonsure was worn in the pre-Christian Ireland and involved shaving the front of the head from ear-to-ear. During the seventh century, fierce debate raged about its validity. Monks in Bayeux came into conflict with local authorities when they adopted this alternative style. The Church ultimately condemned Celtic tonsure, claiming the magician Simon Magus wore it.