What is a fused bulb?

A fused bulb is a bulb that does not glow anymore because its filament is broken. Inside an electric bulb, there is a thin wire called a filament that heats up and produces light when current passes through it. If the filament breaks due to overheating or long use, the circuit inside the bulb is broken, and it stops glowing. Such a bulb is called a fused bulb.