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.
early 15c., to go by, pass (of time), from lapse (n.) and from Latin lapsare "to lose one's footing, slip, slide," from stem of labi "to slip, glide, fall." Meaning "fail in duty or faith" is from 1630s. Meaning "become void, revert due to some failure or non-action by the holder" is from 1726. Related: Lapsed; lapses; lapsing.