Window frames refer to the structure that surrounds a window. There are several synonyms for this term, including window casings, window sashes, and window jambs. Window casings are the visible part of the window frame on the outside of the building. Window sashes are the movable part of the window frame that holds the glass. Window jambs are the vertical parts of the frame on either side of the window opening. Other terms that can be used to describe window frames include window moldings, window trims, or simply, window frames. Regardless of the terminology used, the purpose of the window frame remains the same, which is to hold the glass in place and provide support and stability to the window.