prolapse v.

word-forming element meaning "forward, forth, toward the front" (as in proclaim, proceed); "beforehand, in advance" (prohibit, provide); "taking care of" (procure); "in place of, on behalf of" (proconsul, pronoun); from Latin pro (adv., prep.) "on behalf of, in place of, before, for, in exchange for, just as," which also was used as a first element in compounds and had a collateral form por-.

Also in some cases from cognate Greek pro "before, in front of, sooner," which also was used in Greek as a prefix (as in problem). Both the Latin and Greek words are from PIE *pro- (source also of Sanskrit pra- "before, forward, forth;" Gothic faura "before," Old English fore "before, for, on account of," fram "forward, from;" Old Irish roar "enough"), extended form of root *per- (1) "forward," hence "in front of, before, toward, near," etc.

The common modern sense of "in favor of, favoring" (pro-independence, pro-fluoridation, pro-Soviet, etc.) was not in classical Latin and is attested in English from early 19c.

mid-15c., "elapsing of time, expiration;" also "temporary forfeiture of a legal right" due to some failure or non-action by the holder, from Old French laps "lapse," from Latin lapsus "a slipping and falling, a landslide; flight (of time); falling into error," from labi "to glide, slip, slide, sink, fall; decline, go to ruin," which is of unknown etymology.

Meaning "moral transgression, sin" is from c. 1500; that of "slip of the memory" is 1520s; that of "a falling away from one's faith" is from 1650s.