A lighter is a type of flat-bottomed barge used to transfer goods to and from moored ships. Lighters were traditionally unpowered and were moved and steered using long oars called "sweeps", with their motive power provided by water currents. They were operated by highly skilled workers called lightermen and were a characteristic sight in London's docks until about the 1960s, when technological changes made lighters largely redundant.
The name itself is of uncertain origin, but is believed to possibly derive from an old Dutch or German word, lichten (to lighten or unload).