A motor-vehicle armrest has a base fixed on the vehicle and defining an axis and an armrest part pivotal on the base about the axis and having a first concave surface turned radially inward toward a second convex surface of the base. A wedge-shaped sprag is slidable between the surfaces generally angularly of the axis between a locking position in which the armrest part is arrested relative to the base and a release position in which pivoting of the armrest part with respect to the base is possible. The sprag has a first contact face cooperating with the first surface of the armrest part and a second nonparallel contact face cooperating with the second surface of the base. The sprag is biased into the locking position and can be moved into the release position.