The studio setting in the British programme is called the Den.
The title Dragon's Den uses a deliberately dramatic image for the room where entrepreneurs meet the investors. Contestants walk into the Den, deliver their pitches and answer questions from the Dragons. The setting is a television studio designed to resemble a large, imposing business space rather than a conventional office or meeting room.
The name also creates the programme's central language. The investors are called Dragons, entrepreneurs are described as entering the Den, and a strong pitch may be framed as successfully facing the panel. These labels are branding devices built around the investment format.
The Den should not be confused with the individual Dragons' offices, businesses or homes. Nor is it the name of a separate business-investment company. It is the programme's on-screen meeting space, where proposed investments are discussed before any agreement is subject to further negotiations and checks.