qualm vs sickness

qualm and sickness both are nouns.

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

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

Other hypernyms of qualm include nausea.

qualm (noun)	sickness (noun)
uneasiness about the fitness of an action (particularly for reasons of ethics, morals or propriety)	impairment of normal physiological function affecting part or all of an organism
a mild state of nausea	the state that precedes vomiting
	defectiveness or unsoundness