A casement window with a partial arch head that is vertically split in half is a type of window that features a curved arch at the top of the frame, which is divided into two equal vertical halves. The window operates on a hinge and can be opened and closed using a single sash. These windows are often found in traditional or historical architecture, where their unique shape adds a distinctive design feature while still allowing for a more standard window shape below.

They can be made from various materials, including wood, vinyl, aluminum, or fiberglass, and can be customized with different finishes and hardware options. The vertically split partial arch head shape of these windows creates a visually interesting and unique look, providing a blend of traditional and contemporary design elements.