from side to side
Moving from left to right. The way the boat keeps swaying from side to side is making me nauseous.
from side to side
moving first to one side and then to the other, repeatedly. The pendulum of the clock swings from side to side. The singers swayed from side to side as they sang.
from ˌside to ˈside
moving to the left and then to the right: He shook his head slowly from side to side.The ship rolled from side to side.