The term for a fixed-gear bicycle with no freewheel is a fixie.
A fixie, short for fixed-gear bicycle, has its rear sprocket attached directly to the hub. Because there is no freewheel mechanism, the pedals continue turning whenever the rear wheel turns. The rider therefore cannot coast in the usual way and can influence the bicycle’s motion by resisting or reversing pedal movement.
Fixed-gear bicycles remained standard equipment for track racing because their direct drivetrain is mechanically simple and reliable. In modern cities, fixies also became associated with minimalist commuter bicycles and an urban cycling subculture. Some are built without hand brakes, although braking requirements and safety practices vary by location.
A fixie is not identical to a single-speed bicycle. Both may use one gear ratio, but a conventional single-speed generally has a freewheel, allowing the rider to coast. The defining feature of a fixie is the fixed connection between the pedals and rear wheel, not merely the number of gears.