What does casement mean?
A casement is a window that opens on hinges fixed along one vertical edge, swinging outward or inward much like a door. In modern building practice it most often appears in the compound 'casement window', distinguishing it from sliding sash windows that move up and down in grooves. Casements are common in older houses, cottages, and period architecture, where they are frequently made of timber with leaded glass panes, though contemporary versions may be metal or uPVC. Beyond practical use, the word has a strong literary pedigree: poets have long favored it as a more evocative alternative to 'window', most famously in John Keats's line about 'magic casements, opening on the foam of perilous seas'. The term derives ultimately from Latin capsa, meaning a box or container, via Old French, reflecting the sense of a framed enclosure set into a wall. In everyday speech, however, most people simply say 'window', so casement retains a slightly formal or architectural flavor.
nounA window frame that is hinged on one side and opens outward or inward like a door, or the glazed sash fitted into such a frame.
- A window sash hinged at one side that opens like a door.
- The frame or structure holding such a window.
"She pushed open the casement and leaned out to feel the morning air."
"The cottage still had its original leaded casements, swinging open onto the garden."
"He painted every casement white before the new tenants arrived."
Regular plural; commonly used when describing the windows of a whole building.
"All the casements were flung wide to let the breeze through."
Keats gave us 'magic casements, opening on the foam / Of perilous seas, in faery lands forlorn' — proof this humble window word can carry real poetry.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of casement
Casement entered English in the late Middle Ages from Anglo-Norman and Old French forms built on casse, meaning a box or frame, which itself descends from Latin capsa ('a box, case'). The original sense was a frame or casing set into a wall, later narrowed specifically to a hinged window sash. English words sharing this root include case, encase, and cassette, all preserving the idea of an enclosing container.
How casement is actually used
Most often encountered in the compound 'casement window'. The bare noun carries a slightly literary or architectural register; in everyday speech people usually just say 'window'. It appears frequently in poetry and descriptions of older buildings.
Easily confused with casement
A casement is hinged at the side and swings open, while a sash window slides up and down within its frame.