The Collaborative International Dictionary of English v.0.48:
Prolapsus \Pro*lap"sus\, n. [L.] (Med.) Prolapse. [1913 Webster]WordNet (r) 3.0 (2006):
prolapsus n 1: the slipping or falling out of place of an organ (as the uterus) [syn: prolapse, prolapsus, descensus]