The Collaborative International Dictionary of English v.0.48:

Magdalen \Mag"da*len\, n. [From Mary Magdalene, traditionally
   reported to have been the repentant sinner forgiven by
   Christ. See Luke vii. 36.]
   A reformed prostitute.
   [1913 Webster]

WordNet (r) 3.0 (2006):

magdalen
    n 1: a reformed prostitute