Broken window
Glass that has given way — the boundary between inside and outside violently undone.
A broken window in a dream is the dream's image of the boundary between inside and outside violently undone. Windows let in light and keep out weather; when they break, the room is suddenly continuous with the street, the cold, whatever was meant to stay outside. The dream brings the broken window when something in your life — a private space, a household, an interior peace — has been entered by force or by accident, and the membrane that kept it private is now in pieces on the floor. A break that is already being boarded over is the dream telling you the repair has begun. A break left open with the weather coming in is the dream noting that the breach has not yet been treated as urgent, and what is now inside the room is no longer only what you chose.