A zip-line, zip line, zip-wire, flying fox, or death slide is a pulley suspended on a cable, usually made of stainless steel, mounted on a slope. It is designed to enable cargo or a person propelled by gravity to travel from the top to the bottom of the inclined cable by holding on to, or being attached to, the freely moving pulley. It has been described as essentially a Tyrolean traverse that engages gravity to assist its speed of movement. Its use is not confined to adventure sport, recreation, or tourism, although modern-day usage tends to favor those meanings.

A Tyrolean traverse is a method of crossing through free space between two high points on a rope without a hanging cart or cart equivalent. This is used in a range of mountaineering activities: rock climbing, technical tree climbing, caving, water crossings and mountain rescue. A zip-line is in essence a Tyrolean traverse which is traveled down quickly with the assistance of gravity. Several sources claim that the name comes from the Tyrolean Alps, where climbers are said to have developed the system in the late nineteenth and early twentieth centuries.