defervescence vs hiatus

defervescence and hiatus both are nouns.

Word	Noun	Adjective	Verb	Adverb
defervescence	Yes	No	No	No
hiatus	Yes	No	No	No

As nouns, hiatus is a hypernym of defervescence; that is, hiatus is a word with a broader meaning than defervescence:

defervescence: abatement of a fever as indicated by a reduction in body temperature
hiatus: an interruption in the intensity or amount of something

Other hypernyms of defervescence include abatement, reprieve, respite, suspension.

defervescence (noun)	hiatus (noun)
abatement of a fever as indicated by a reduction in body temperature	a natural opening or perforation through a bone or a membranous structure
	a missing piece (as a gap in a manuscript)
	an interruption in the intensity or amount of something