Source : Webster's Revised Unabridged Dictionary (1913)

Exposition \Ex`po*si"tion\, n. [L. expositio, fr. exponere,
   expositum: cf. F. exposition. See {Expound}.]
   1. The act of exposing or laying open; a setting out or
      displaying to public view.

   2. The act of expounding or of laying open the sense or
      meaning of an author, or a passage; explanation;
      interpretation; the sense put upon a passage; a law, or
      the like, by an interpreter; hence, a work containing
      explanations or interpretations; a commentary.

            You know the law; your exposition Hath been most
            sound.                                --Shak.

   3. Situation or position with reference to direction of view
      or accessibility to influence of sun, wind, etc.;
      exposure; as, an easterly exposition; an exposition to the
      sun. [Obs.] --Arbuthnot.

   4. A public exhibition or show, as of industrial and artistic
      productions; as, the Paris Exposition of 1878. [A
      Gallicism]

Source : WordNet®

exposition
     n 1: a systematic interpretation or explanation (usually written)
          of a specific topic [syn: {expounding}]
     2: a collection of things (goods or works of art etc.) for
        public display [syn: {exhibition}, {expo}]
     3: an account that sets forth the meaning or intent of a
        writing or discourse; "we would have understood the play
        better if there had been some initial exposition of the
        background"