pro·lapse 
(prō-lăps) Medicine
(prō-lăps) Medicine intr.v. pro·lapsed, pro·laps·ing, pro·laps·es
To fall or slip out of place.
n. prolapse (prōlăps′, prō-lăps) also pro·lap·sus (prō-lăpsəs)
The falling down or slipping out of place of an organ or part, such as the uterus.
[Latin prōlābī, prōlāps-, to fall down : prō-, forward; see PRO-1 + lābī, to fall.]