A tonsure is the shaved part on the top of a monk's or priest's head. In the old Catholic style, the hair on top was cut away and a ring of hair was left all around, so the bald circle looked a bit like a crown. It was not a haircut for looking good — it was a sign. It said: this man belongs to the church now, he has given up normal life, he does not care about his appearance the way other men do. Different churches did it differently. Eastern (Orthodox) monks often shaved the whole head instead. Buddhist monks also shave, but we do not usually call that a tonsure — the word carries a Christian, and especially a Western medieval, feeling, so you will meet it most often in history books, in stories about monasteries, and in art. The word can mean two things at once: the bald patch itself, and the ceremony of cutting it, the moment when a young man officially entered religious life. There is also a verb, to tonsure someone, meaning to cut their hair this way, though the verb is rare and formal. Note that the Roman Catholic Church stopped requiring the tonsure in 1972, so today the word is mostly about the past. English speakers sometimes stretch it as a small joke: a man going bald on top, with hair still around the sides, may be said to have a natural tonsure.

（修士的）剃髮、頭頂剃光的圓형