hypopnea vs breathing

hypopnea and breathing both are nouns.

Word	Noun	Adjective	Verb	Adverb
hypopnea	Yes	No	No	No
breathing	Yes	Yes	No	No

As nouns, breathing is a hypernym of hypopnea; that is, breathing is a word with a broader meaning than hypopnea:

hypopnea: slow or shallow breathing
breathing: the bodily process of inhalation and exhalation; the process of taking in oxygen from inhaled air and releasing carbon dioxide by exhalation

Other hypernyms of hypopnea include external respiration, respiration, ventilation.

hypopnea (noun)	breathing (noun)
slow or shallow breathing	the bodily process of inhalation and exhalation; the process of taking in oxygen from inhaled air and releasing carbon dioxide by exhalation

hypopnea (adjective)	breathing (adjective)
	passing or able to pass air in and out of the lungs normally; sometimes used in combination