What does "seasickness" mean?

Nausea, dizziness etc caused by the motion of a ship; a form of motion sickness.

What is a synonym for "seasickness"?

Common synonyms include: kinetosis, mal de mer, motion sickness, naupathia, nausea, qualm.

Pronounced //ˈsiːsɪk.nəs//.

/ˈsiːsɪk.nəs/ noun

noun ·Rare ·Advanced level

Noun

1
Nausea, dizziness etc caused by the motion of a ship; a form of motion sickness. uncountable, usually
2
motion sickness experienced while traveling on water wordnet

"Take seasickness medication at least an hour before you board."

From seasick + -ness and/or sea + sickness. Compare Middle English seknesse of the see (“seasickness”, literally “sickness of the sea”).