Suffering from sickness or nausea caused by the motion of a ship at sea.
She felt seasick on the boat to the island.
Seasick passengers clung to the ship's railing as waves tossed it to and fro.
The rocking motion of the boat left her feeling seasick and queasy.
Even with medication, some people are prone to becoming seasick during rough sea conditions.
The crew provided seasick bags for those struggling with the ocean's movement.
