window

Windows are very useful things.

You can catch sight of something or someone through a window. From outside in. And from inside out.

You can open a window to let the smell of perfume or gunpowder escape.

It is even possible to dispose of a dead body out a window.

Or you can hide behind the drapes when someone comes home unexpectedly and you've been searching the place.

Oh, yes. Windows are very useful.