word-forming element meaning "after," from Latin post "behind, after, afterward," from *pos-ti (source also of Arcadian pos, Doric poti "toward, to, near, close by;" Old Church Slavonic po "behind, after," pozdu "late;" Lithuanian pas "at, by"), from PIE *apo- (source also of Greek apo "from," Latin ab "away from" see apo-).
"introductory performance; a preliminary to an action event or work," 1560s, from French prélude "notes sung or played to test the voice or instrument" (1530s), from Medieval Latin preludium "prelude, preliminary," from Latin praeludere "to play beforehand for practice, preface," from prae- "before" (see pre-) + ludere "to play" (see ludicrous). Purely musical sense of "movement or piece forming the introduction to a musical work" is attested in English by 1650s. Related: Preludial; prelusive; prelusory; preludious; prelusion.
Others are reading
Definitions of postlude
a voluntary played at the end of a religious service;