What is Tonsure?
A man with a tonsured head
Tonsure means to cut off someone's hair. Monks
in the Middle Ages generally showed that they were monks by cutting
their hair short (when most men wore theirs long) and especially by
shaving a bald spot in the middle of the back of their heads.
Because you could not be king (or emperor) if you were a monk, sometimes kings forced their rivals to have their hair tonsured, so that nobody would try to make them king.
Among the Franks, just having short hair by itself seems to have been enough to keep you from becoming king. And among the Visigoths, both men and women had their hair cut off as punishment for a wide variety of crimes, as well as to keep them from becoming king.
To find out more about medieval Christian monks, check out these books from Amazon or from your library: