Refers to a place where gambling takes place, often with a rough or dangerous atmosphere. The term is somewhat dated and evokes the image of traditional, often illegal, gambling joints.
He was gambling all night at the gambling den.
カジノ is the modern loanword for a casino, typically a legal, Western-style establishment, unlike the traditional and often shady 鉄火場.
The term combines 鉄火 (tekka, 'red-hot iron' or 'gunfire'), suggesting a heated, intense atmosphere, with 場 (ba, 'place'). The exact historical derivation is uncertain, but it likely refers to the fiery, high-stakes nature of the gambling that occurred there.