The Collaborative International Dictionary of English v.0.48:

Loreto nuns \Lo*ret"o nuns\, or Loretto nuns \Lo*ret"to nuns\
   [From Loreto, a city in Italy famous for its Holy House, said
   to be that in which Jesus lived, brought by angels from
   Nazareth.] (R. C. Ch.)
   Members of a congregation of nuns founded by Mrs. Mary Teresa
   Ball, near Dublin, Ireland, in 1822, and now spread over
   Ireland, India, Canada, and the United States. The nuns are
   called also Ladies of Loreto. They are engaged in teaching
   girls.
   [Webster 1913 Suppl.]