an introductory or preliminary performance, action, or event
a musical section or movement introducing the theme or chief subject or serving as an introduction, e.g. to an opera
the introductory section of a literary work
a short separate concert piece, usu for piano or orchestra
preludial /priʹl(y)oohdi·əl/ adj
[early French prelude from medieval Latin praeludium, from praeludere to play beforehand, from prae- + ludere to play]