A measure of the longitudinal curvature of the hull. Kayaks can be heavily rockered, like WhiteWater kayaks, which often have a "banana-shape" rocker, or rocker in the bow only. A kayak could have rocker in the stern only, but this is rare and probably difficult to control. A kayak with heavy rocker can pitch more than a boat with low rocker.
How a kayaks ends are shaped in relation to the volume in the middle of the craft.
Stability is a factor that isn't a direct measure of a boat's handling, but the kayak's ability or lack of ability to be easily edged, leaned, or rolled will affect other handling factors.