The Collaborative International Dictionary of English v.0.48:

Prelude \Pre*lude"\, v. t.
   1. To introduce with a previous performance; to play or
      perform a prelude to; as, to prelude a concert with a
      lively air.
      [1913 Webster]

   2. To serve as prelude to; to precede as introductory.
      [1913 Webster]

            [Music] preluding some great tragedy. --Longfellow
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Prelude \Pre"lude\, n. [F. pr['e]lude (cf. It. preludio, LL.
   praeludium), fr. L. prae before + ludus play. See Prelude,
   v. t.]
   An introductory performance, preceding and preparing for the
   principal matter; a preliminary part, movement, strain, etc.;
   especially (Mus.), a strain introducing the theme or chief
   subject; a movement introductory to a fugue, yet independent;
   -- with recent composers often synonymous with overture.
   [1913 Webster]

         The last Georgic was a good prelude to the Aenis
                                                  --Addison.
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         The cause is more than the prelude, the effect is more
         than the sequel, of the fact.            --Whewell.
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   Syn: Preface; introduction; preliminary; preamble;
        forerunner; harbinger; precursor.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Prelude \Pre*lude"\, v. i. [imp. & p. p. Preluded; p. pr. &
   vb. n. Preluding.] [L. praeludere, praelusum; prae before +
   ludere to play: cf. F. pr['e]luder. See Ludicrous.]
   To play an introduction or prelude; to give a prefatory
   performance; to serve as prelude.
   [1913 Webster]

         The musicians preluded on their instruments. --Sir. W.
                                                  Scott.
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         We are preluding too largely, and must come at once to
         the point.                               --Jeffrey.
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WordNet (r) 3.0 (2006):

prelude
    n 1: something that serves as a preceding event or introduces
         what follows; "training is a necessary preliminary to
         employment"; "drinks were the overture to dinner" [syn:
         preliminary, overture, prelude]
    2: music that precedes a fugue or introduces an act in an opera
    v 1: serve as a prelude or opening to
    2: play as a prelude

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "prelude":
   Vorspiel, antecedence, antecedency, anteposition, anteriority,
   avant-propos, breakthrough, concert overture, curtain raiser,
   descant, dominion, dramatic overture, exordium, foreword,
   front matter, front position, frontispiece, innovation, introduce,
   introduction, leap, operatic overture, overture, postulate,
   preamble, precedence, precedency, preceding, precession, precursor,
   preface, preference, prefix, prefixation, prefixture, preliminary,
   premise, presupposition, priority, proem, prolegomena,
   prolegomenon, prolepsis, prologize, prologue, protasis, prothesis,
   superiority, the lead, top priority, urgency, vamp, verse,
   voluntary