Other forms: seasickest
If you're seasick, you feel unwell because of the rocking motion a boat or ship makes as it travels on the water. A chronically seasick ship's captain might have to look for a new job.
Some people become nauseated and dizzy even when they're briefly on a boat — these are the easily seasick travelers. Others are normally fine traveling by boat but become seasick during storms, when the vessel is tossed around on the waves. If the sensation of movement tends to make you seasick, you may be affected by long car trips and airplane flights as well.