A hieromonk, also called a priestmonk, is a monk who is also a priest in the Orthodox Church and Eastern Catholicism.

A hieromonk can be either a monk who has been ordained to the priesthood or a priest who has received monastic tonsure. When a married priest's wife dies, it is not uncommon for him to become a monk, since the Church forbids clergy to enter into a second marriage after ordination. (source)