A seat, plank, or cradle attached to a rope and pulley whereby the seated individual can be hoisted up to work at an elevated or otherwise difficult to reach position.

Bosun is an abbreviated form of boatswain, who would be the hoistee on a ship. Bosun's chairs are not limited to use on a boat: they are currently used in the repair and maintenance of utility poles, theater lighting, office windows, industrial chimneys, and construction sites. There is also a model marketed to rock climbers who like to take lunch breaks halfway up their ascent.