FRAME ADAPTER, WINDOW INSERT WITH A FRAME ADAPTER AND VEHICLE WITH A FRAME ADAPTER

A frame adapter (2) for a movable window sash (10) comprises an adapter frame (3) that frames a window opening (6) which is bounded by a planar opening edge (7), wherein the adapter frame (3) has a fastening edge (4) along an outer frame perimeter which has, at least in sections, a circumferentially curved course. A window insert (1) for a vehicle comprises a frame adapter (2) that can be inserted into a body opening, with a movable window sash (10) arranged in the window opening (6) of the frame adapter (2). The window sash (10) is pivotably mounted on the adapter frame (3) by means of a hinge device (15). The window sash (10) can have a frameless window pane (11) or a window pane (11) framed by a window frame (12).