fortochka

 A fortochka (Russian: фо́рточка, IPA: [ˈfortətɕkə] (About this soundlisten)) is a small ventilation window.[1] It usually spans the frame of one window pane and opens on hinges independently of the whole window. Fortochkas are in common use in Russia, other post-Soviet states (Ukrainian: кватирка, kvatyrka), and Finland (Finnish: tuuletusikkuna).

A window with a fortochka (in the upper left corner)

A fortochka can be used for ventilation during cold winters, when opening a whole window would be impractical for heat conservation purposes.[2]

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 Metasyntactic variable, which is released under the 
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