compline (n.)

the last canonical service of the day, early 13c., cumplie, compelin, from Old French complie (12c.), from Medieval Latin completa, from Latin completa (hora), from completus (see complete (adj.)); with unetymological -n-. So called because the service usually completes the religious exercises of the day. Originally it was said after the evening meal and before retiring to bed, but in later medieval times it shifted to immediately after vespers.