Fortochka

A fortochka (Russian: фо́рточка, IPA: [ˈfortətɕkə] ⓘ) is a small ventilation window generally not greater than 35x45 cm.

Fortochkas are in common use in Russia, other post-Soviet states (Ukrainian: кватирка, kvatyrka), and Finland (Finnish: tuuletusikkuna).

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

[2] The window was designed by Italian architect Francesco Bartolomeo Rastrelli for the Winter Palace in St. Petersburg in 1754.

[4] Someone referred to as a "fortochnik" is a criminal specializing in the challenging art of sneaking into and out of a fortochka.