Meaning of Chicago window

Chica'go win'dow

Pronunciation: [key]
  1. a composite window, horizontal in character, consisting of a large, fixed sheet of glass between two vertical windows with sash for ventilation, first popularized in commercial buildings in Chicago in the 1880s and 1890s.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.