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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

Depression is one of the leading causes of disability among people ages 16 to 24, Casement said.

From Science Daily • Jan. 7, 2026

Casement Park will not be finished in time for the tournament, while Hill Dickinson Stadium has been selected as one of nine host stadiums.

From BBC • Nov. 28, 2025

Matches were also set to be played in Northern Ireland, but Belfast's Casement Park was removed as an option because of a lack of funding.

From BBC • Nov. 12, 2025

For your information I enclose Zimmerman’s letter to Sir Roger, and also the text of Articles 6 and 7, being part of our first agreement with Sir Roger Casement.

From The Moonlit Way by Chambers, Robert W. (Robert William)