Pronation describes an inward rotation. At the forearm, it means the rotation in which the palm faces downwards, starting from the neutral position with the palm facing up.
At the foot, pronation describes a combined lowering of the inner edge of the foot with slight outward rotation. Controlled pronation during the rolling motion of walking and running is physiological and serves shock absorption. Only clearly increased pronation (overpronation) is considered notable in movement analyses. Its counterpart is supination.