window

But then I had the [massive] flintlock by me for protection. ¶[…]The linen-press and a chest on the top of it formed, however, a very good gun-carriage; and, thus mounted, aim could be taken out of the window at the old mare feeding in the meadow below by the brook, and a 'bead' could be drawn upon Molly, the dairymaid, kissing the fogger behind the hedge,[…].

There is an hour or two, after the passengers have embarked, which is disquieting and fussy.[…]Passengers wander restlessly about or hurry, with futile energy, from place to place. Pushing men hustle each other at the windows of the purser's office, under pretence of expecting letters or despatching telegrams.

launch window;  window of opportunity;  You have a two-hour window of clear weather to finish working on the lawn.

His journal provides a window into his otherwise obscure life.

In this case, a band-pass filter using a range or window of frequencies is appropriate to isolate the frequency or the group of frequencies that characterize a specific cycle.

till he has windows on his bread and butter