window sash

the frame holding the pane of a window.

Origin of window sash

First recorded in 1755–65

Under this impression she raised the window-sash—her bedroom being on the upper floor—and looked timidly out.

Jeff Benson, or the Young Coastguardsman |R.M. Ballantyne
The window-sash was down all but a little crack to let in air, and I raised it so slowly and gently that I made no noise.

The Stories of the Three Burglars |Frank Richard Stockton
The ODonoghue laughed as he witnessed the discomfiture of the ragged mob, and let down the window-sash to watch the scene.

The O'Donoghue |Charles James Lever
The window-sash aloft opens—for the third time; would to Heaven he could read the true astrology of the stars!

Blackwood's Edinburgh Magazine, Vol. 66 No.406, August 1849 |Various

Jimmie whistled the signal after having pushed up the window-sash some inches.

Whilomville Stories |Stephen Crane

window sash

a glazed window frame, esp one that opens