The Collaborative International Dictionary of English v.0.48:

Prolapse \Pro*lapse"\, v. i.
   To fall down or out; to protrude.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Prolapse \Pro*lapse"\, n. [L. prolapsus, fr. prolapsus, p. p. of
   prolabi to fall forward; pro forward + labi to glide, fall.]
   (Med.)
   The falling down of a part through the orifice with which it
   is naturally connected, especially of the uterus or the
   rectum. --Dunglison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

prolapse
    n 1: the slipping or falling out of place of an organ (as the
         uterus) [syn: prolapse, prolapsus, descensus]
    v 1: slip or fall out of place, as of body parts; "prolapsed
         rectum"