Not too happy with you using autism to call someone dumb, but I'll leave this up assuming it was just a one-off.
Definition of sash for Students. 1  1 : a frame for a pane of glass in a door or window. 2  2 : the movable part of a window.
The name hung sash window, which is more usual in the United States than in the United Kingdom, typically refers to a double-hung window with two sashes that can move up and down in the window frame.