Oblate

noun

1. A person dedicated to a life of religion or monasticism, especially a member of an order without religious vows or a lay member of a religious community.
2. A child given up by its parents into the keeping or dedication of a religious order or house.

   "2007, The Venerable Bede started as an oblate at St Paul's, Jarrow, but by the time of his death in 735 was surely the most learned man in Europe. — Tom Shippey, ‘I Lerne Song’, London Review of Books 29:4, p. 19"