Compline comes from a Latin word meaning to complete, and so implies
a way to round off the day.
The roots of this practice of night prayer trace back to the Jewish habit of praying at fixed hours of the day, which was continued by early Christians. Saint Benedict organized daily set prayers into seven ‘Day Hours’ and one ‘Night Office’ in the fifth century. Compline was the last and simpler of the ‘Day Hours’. In the 16th century Archbishop Thomas Cranmer reduced three of the daily ‘hours’ into a Morning Prayer, jettisoned three others, and combined Compline and Vespers into Evening Prayer (or Evensong, when sung by a choir).
The Episcopal Church revived a form of compline as a distinct service in 1914, alongside a restored noonday prayer.