window (n.)
c.1200, literally "wind eye," from Old Norse vindauga, from vindr "wind" (see wind (n.1)) + auga "eye" (see eye (n.)). Replaced Old English eagþyrl, literally "eye-hole," and eagduru, literally "eye-door."

Originally an unglazed hole in a roof, most Germanic languages adopted a version of Latin fenestra to describe the glass version (such as German Fenster, Swedish fönster), and English used fenester as a parallel word till mid-16c. Window dressing is first recorded 1790; figurative sense is from 1898. Window seat is attested from 1778. Window of opportunity (1979) is from earlier figurative use in U.S. space program, such as launch window (1963). Window-shopping is recorded from 1904.
"Window shopping, according to the women, is the king of outdoor sports. Whenever a woman gets down town and has 2 or 3 hours and no money to spend, she goes window shopping. She gives the Poiret gowns and the thousand dollar furs the double O and then kids herself into believing she'd look like Lillian Russell or Beverly Bayne if she had 'em on. It's great for developing the imagination and one of the great secrets of conserving the bankroll. ..." ["Motor Age," Jan. 27, 1916]