noun
iron bars; iron grille; iron lattice
Refers to a physical barrier made of iron bars, such as a window grille, fence, or cage.
窓には鉄格子がはめられている。
The window is fitted with iron bars.
古い家の門には鉄格子が使われている。
Iron grilles are used on the gate of the old house.
noun
Colloquial metonymy: iron bars as a symbol for prison. Often used in expressions like 鉄格子の向こう or 鉄格子の中.
彼は鉄格子の向こうで反省している。
He is reflecting on his actions behind bars.
あんなことをしたら、鉄格子行きだよ。
If you do something like that, you'll end up in prison.