In a number of Christian traditions, including Eastern Orthodoxy, Catholicism, Lutheranism and Anglicanism, a confessor is a priest who hears the confessions of penitents and pronounces absolution.
[1] During the Diocletianic Persecution, a number of Christians had, under torture or threat thereof, weakened in their profession of the faith.
It became the practice of the penitents to go to the Confessors, who had willingly suffered for the faith and survived, to plead their case and effect their restoration to communion.
Historically, priests were sometimes tested by officers of the church called examiners, before being granted this authority.
It is standard practice for a religious community of women, whether enclosed or just very large, to have one or several priests serving their spiritual needs, including being their confessor.