Source : Webster's Revised Unabridged Dictionary (1913)

Knickerbockers \Knick"er*bock`ers\, n. pl.
   The name for a style of short breeches; smallclothes.

Source : WordNet®

knickerbockers
     n : trousers ending above the knee [syn: {breeches}, {knee
         breeches}, {knee pants}, {knickers}]