NOUN (3)

1. a buffoon in modern pantomimes; the butt of jokes;

2. a character in the commedia dell'arte; portrayed as a foolish old man;

3. trousers worn in former times;

The Collaborative International Dictionary of English v.0.48:

Pantaloon \Pan`ta*loon"\, n. [F. pantalon, fr. It. pantalone, a
   masked character in the Italian comedy, who wore breeches and
   stockings that were all of one piece, from Pantaleone, the
   patron saint of Venice, which, as a baptismal name, is very
   frequent among the Venetians, and is applied to them by the
   other Italians as a nickname, fr. Gr. Pantale`wn, lit., all
   lion, a Greek personal name.]
   1. A ridiculous character, or an old dotard, in the Italian
      comedy; also, a buffoon in pantomimes. --Addison.
      [1913 Webster]

            The sixth age shifts
            Into the lean and slippered pantaloon. --Shak.
      [1913 Webster]

   2. pl. A bifurcated garment for a man, covering the body from
      the waist downwards, and consisting of breeches and
      stockings in one.
      [1913 Webster]

   3. pl. In recent times, a loose-fitting variety of
      Trousers, often of less than ankle length.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

Pantaloon
    n 1: a buffoon in modern pantomimes; the butt of jokes
    2: a character in the commedia dell'arte; portrayed as a foolish
       old man
    3: trousers worn in former times