casement

 
Pronunciation: /ˈkeɪsm(ə)nt/

noun

  • a window or part of a window set on a vertical hinge so that it opens like a door.
  • literary a window of any kind.
  • the sash of a sash window.

Origin:

late Middle English (as an architectural term denoting a hollow moulding): from Anglo-Latin cassimentum, from cassa, from Latin capsa (see case2)