incredulity vs doubt

incredulity and doubt both are nouns.

Word	Noun	Adjective	Verb	Adverb
incredulity	Yes	No	No	No
doubt	Yes	No	Yes	No

As nouns, doubt is a hypernym of incredulity; that is, doubt is a word with a broader meaning than incredulity:

Other hypernyms of incredulity include doubtfulness, dubiety, dubiousness, incertitude, uncertainty.

incredulity (noun)	doubt (noun)
doubt about the truth of something	uncertainty about the truth or factuality or existence of something
	the state of being unsure of something

incredulity (verb)	doubt (verb)
	consider unlikely
	lack confidence in