A window. When Czechs had poor administrators, they threw them out the window. The latin based version version of this is “defenestration”, and the Czech word is “defenestrace”, one of my personal favorites that I try to work into every conversation. “Hele vole, to je pěkná defenestrace, co?”. Windows are so common here, that if you happen to drink, say, half a bottle of Absynthe, you would experience “okno” in the sense of a drunken black out. While in politically correct countries your pals would urge you to seek treatment and counseling after such an episode, here they chuckle and relate their most recent “okno” story.