Watershed

A watershed is a significant turning point, a division, a transition or change of direction and acquired this figurative meaning from the mid-19th century. The word itself is first attested from the late 18th/early 19th century and originally referred to the dividing/meeting point, usually a ridge, between the confluences of two river systems. The shed in watershed has nothing to do with shed as in garden shed but derives from the Old High German scheiden meaning a divide. The meaning given here is the British one because watershed in America refers to a river basin or a river catchment area rather than a divide. This is probably due to confusion with the other meaning of shed, meaning a storage place.