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."