Tilted, off level, off center (like a knot of hair not in the middle, head bent to one side, water in a glass sitting on a slope).
That person has (his head) tilted; perhaps his neck is hurting.
To lean to one side, tilt to one side (not being vertical as s.t. placed on a slope or not horizontal as s.t. long tilted sideways).
The reason that the water in the barrel ran out is because it is leaning to one side.
The ferry keeps tilting because there are waves.