mal de mer vs seasickness

mal de mer and seasickness both are nouns.

Word	Noun	Adjective	Verb	Adverb
mal de mer	Yes	No	No	No
seasickness	Yes	No	No	No

As nouns, mal de mer and seasickness are synonyms defined as:

mal de mer and seasickness: motion sickness experienced while traveling on water

Other synonyms of mal de mer include naupathia.

mal de mer (noun)	seasickness (noun)
motion sickness experienced while traveling on water	motion sickness experienced while traveling on water