A sloper is a type of hold that literally slopes towards the climber. They are often tricky to use as there is no obvious hold as such to grab onto. Slopers require the climber to use friction to pull on the rock and as such a more open, flat hand approach is required. Slopers occur often in outdoor climbing and bouldering, but all good climbing walls will also include slopers in their routes.

A natural sloper.
Photo credit:  Planet Fear.

A “sloper” climbing hold.
Photo credit:  Big Climbing Holds.