Which term describes wood trim molding around a door or window?

The term that describes wood trim molding around a door or window is casing. Casing serves both functional and aesthetic purposes. It frames the opening, helping to provide a finished look to the installation of the door or window while also covering any gaps between the frame and the surrounding wall. Casing can be made from various materials and is often designed to complement the style of the home, contributing to its overall architectural appeal.

The other options refer to different construction elements. For example, chase generally refers to a vertical space or duct in walls for running pipes, wiring, or ventilation. Ceiling joists are horizontal supports that hold up the ceiling and are not related to door or window trim. Cap flashing is a moisture control element that is installed to prevent water penetration at joints and is used primarily in roofing, distinctly separate from the trim work associated with doors and windows.