Doctor of the Church
Concise Oxford English Dictionary © 2008 Oxford University Press:
Doctor of the Church
▶noun one of the early Christian theologians regarded as especially authoritative in the Western Church (particularly St Augustine of Hippo, St Jerome, St Ambrose, and St Gregory the Great) or later so designated by the Pope (e.g. St Thomas Aquinas, St Teresa of Ávila).
'Doctor of the Church' also found in these Oxford entries:

