Gas fill. A gas other than air, usually argon or krypton, placed between window or skylight glazing panes to reduce the U-factor by suppressing conduction and convection.
Glass. An inorganic transparent material composed of silica (sand), soda (sodium carbonate), and lime (calcium carbonate) with small quantities of alumina, boric, or magnesia oxides.
Glazing. The glass or plastic panes in a window, door, or skylight.
Glazing bead. A molding or stop around the inside of a window frame to hold the glass in place.
Greenhouse window. A three-dimensional window that projects from the exterior wall and usually has glazing on all sides except the bottom, which serves as a shelf.