motion sickness vs sickness

motion sickness and sickness both are nouns.

Word	Noun	Adjective	Verb	Adverb
motion sickness	Yes	No	No	No
sickness	Yes	No	No	No

As nouns, sickness is a hypernym of motion sickness; that is, sickness is a word with a broader meaning than motion sickness:

motion sickness: the state of being dizzy or nauseated because of the motions that occur while traveling in or on a moving vehicle
sickness: the state that precedes vomiting

Other hypernyms of motion sickness include ailment, complaint, ill, nausea.

motion sickness (noun)	sickness (noun)
the state of being dizzy or nauseated because of the motions that occur while traveling in or on a moving vehicle	impairment of normal physiological function affecting part or all of an organism
	the state that precedes vomiting
	defectiveness or unsoundness