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• casement
  casement

  noun

  a window sash opening on hinges that are generally attached to the upright side of its frame.
• Casement
  Casement

  noun

  (Sir) Roger (David), 1864–1916, Irish patriot: hanged by the British for treason.

casement

¹ American  

[keys-muhnt] / ˈkeɪs mənt /

noun

1. a window sash opening on hinges that are generally attached to the upright side of its frame.

2. Also called casement window.  a window with such a sash or sashes.

3. a casing or covering.

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Casement ² American  

[keys-muhnt] / ˈkeɪs mənt /

noun

1. (Sir) Roger (David), 1864–1916, Irish patriot: hanged by the British for treason.

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casement ¹ British  

/ ˈkeɪsmənt /

noun

1. a window frame that is hinged on one side

2. a window containing frames hinged at the side or at the top or bottom

3. a poetic word for window

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Casement ² British  

/ ˈkeɪsmənt /

noun

1. Sir Roger ( David ). 1864–1916, British diplomat and Irish nationalist: hanged by the British for treason in attempting to gain German support for Irish independence

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Other Word Forms

• casemented
  adjective

Etymology

Origin of casement

1375–1425; late Middle English. See case ², -ment

Explanation

A casement is a type of window that swings open on a hinge, like a door. Open the casements in the kitchen and let the breeze come in! Before the invention of the sash window, which slides up and down, casements were very common. Today, you're more likely to see casement windows in European homes than in the U.S. Extremely old houses, especially those built before the 17th century, commonly have casement windows with leaded glass panes. Experts guess that the word casement comes from the Old French enchassement, "window frame."

Example Sentences

"Instead of being a morning lark you're going to become more of a night owl," Casement explained.

From Science Daily • Jan. 7, 2026

"It makes that age range of particular interest in trying to understand risk factors for depression and how those might relate to delivery of interventions," Casement said.

From Science Daily • Jan. 7, 2026

The executive had previously committed £62m towards the construction of Casement Park.

From BBC • Jan. 6, 2026

Also included in the draft budget is an inflationary uplift of some £52.4m for the redevelopment of Casement Park as well as an uplift for sub-regional football stadia, also in line with inflation.

From BBC • Jan. 6, 2026

Casement had last been heard of in Germany, where he had attempted to induce Irish prisoners of war to join an anti-British expedition to Ireland.

From Raemaekers' Cartoon History of the War, Volume 2 The Second Twelve Months of War by Raemaekers, Louis