Lewis & Short

sanctĭmōnĭālis, e, adj. [sanctimonia], holy; of Christians, pious, religious (late Lat.): vita, i. e. a monastic life, Cod. Just. 1, 3, 56: mulier, i. e. a nun, ib. 1, 2, 13.
As subst.: sanctĭmōnĭālis, is, f., a nun, Aug. Ep. 169; id. Retract. 2, 22.
Adv.: sanctĭmōnĭālĭter, holily, piously: degere, i. e. in a cloister, Cod. Just. 1, 3, 56.