NOUN (3)

1. something or someone seen (especially a notable or unusual sight);
- Example: "the tragic spectacle of cripples trying to escape"

2. an elaborate and remarkable display on a lavish scale;

3. a blunder that makes you look ridiculous; used in the phrase `make a spectacle of'; yourself;

The Collaborative International Dictionary of English v.0.48:

Spectacle \Spec"ta*cle\, n. [F., fr. L. spectaculum, fr.
   spectare to look at, to behold, v. intens. fr. specere. See
   Spy.]
   1. Something exhibited to view; usually, something presented
      to view as extraordinary, or as unusual and worthy of
      special notice; a remarkable or noteworthy sight; a show;
      a pageant; a gazingstock.
      [1913 Webster]

            O, piteous spectacle? O, bloody times! --Shak.
      [1913 Webster]

   2. A spy-glass; a looking-glass. [Obs.]
      [1913 Webster]

            Poverty a spectacle is, as thinketh me,
            Through which he may his very friends see.
                                                  --Chaucer.
      [1913 Webster]

   3. pl. An optical instrument consisting of two lenses set in
      a light frame, and worn to assist sight, to obviate some
      defect in the organs of vision, or to shield the eyes from
      bright light.
      [1913 Webster]

   4. pl. Fig.: An aid to the intellectual sight.
      [1913 Webster]

            Shakespeare . . . needed not the spectacles of books
            to read nature.                       --Dryden.
      [1913 Webster]

   Syn: Show; sight; exhibition; representation; pageant.
        [1913 Webster]

WordNet (r) 3.0 (2006):

spectacle
    n 1: something or someone seen (especially a notable or unusual
         sight); "the tragic spectacle of cripples trying to escape"
    2: an elaborate and remarkable display on a lavish scale
    3: a blunder that makes you look ridiculous; used in the phrase
       `make a spectacle of' yourself