Chicago window
window divided into a large fixed sash and narrow movable sashes on each side, filling a structural bay
en-GB/ʃɪˈkɑːɡəʊ ˈwɪndəʊ/
en-US/ʃəˈkɑˌɡoʊ ˈwɪndoʊ/
window divided into a large fixed sash and narrow movable sashes on each side, filling a structural bay