window stool
Webster's Dictionary (GCIDE)
1.A single seat with three or four legs and without a back, made in various forms for various uses. [1913 Webster]
2.A seat used in evacuating the bowels; hence, an evacuation; a discharge from the bowels. [1913 Webster]
3.A stool pigeon, or decoy bird. [U. S.] [1913 Webster]
4.(Naut.) A small channel on the side of a vessel, for the dead-eyes of the backstays. --Totten. [1913 Webster]
5.A bishop's seat or see; a bishop-stool. --J. P. Peters. [1913 Webster]
6.A bench or form for resting the feet or the knees; a footstool; as, a kneeling stool. [1913 Webster]
7.Material, such as oyster shells, spread on the sea bottom for oyster spat to adhere to. [Local, U.S.] [1913 Webster]
Stool of a window, or Window stool (Arch.), the flat piece upon which the window shuts down, and which corresponds to the sill of a door; in the United States, the narrow shelf fitted on the inside against the actual sill upon which the sash descends. This is called a window seat when broad and low enough to be used as a seat.
Stool of repentance, the cuttystool. [Scot.]
Stool pigeon, a pigeon used as a decoy to draw others within a net; hence, a person used as a decoy for others. [1913 Webster]