hopper ventilator

hopper light

hopper light
1. A window sash which opens inward and is hinged at the bottom; when open, air passes over the top of the sash; also called hopper vent or hopper ventilator.
2. A window sash which opens inward and is hinged at each side; when open, most of the air passes over the top of the sash but there is some flow through a narrower opening along the bottom.