The exterior wood or vinyl trim that goes between the window jamb and the siding is called the brick mould trim.

Outside casing around window to cover jambs and through which nails are driven to install the window. Casing: Inside casing is a flat, decorative moulding which covers the inside edge of the jambs and the rough openings between the window unit and the wall. Outside casing (or Brick Mould) serves the same purpose, while it also is an installation device through which nails are driven to install the window unit into the wall.

Is used as exterior door and window casing. It is a thick moulding, providing a surface for brick or other siding to butt against.