When talking about window glass, there are several synonyms that can be used depending on the context. The most common synonym is simply "glass," which can be used to refer to any type of glass used in windows. Another synonym is "pane," which specifically refers to a single sheet of glass within a window frame. "Glazing" is a term that can be used to describe the installation or process of placing glass into a window frame. Other synonyms for window glass include "porthole," "portlight," and "fenestration," which is a more technical term often used in the architecture and construction industries.