incredulity vs incertitude

incredulity and incertitude both are nouns.

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

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

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

incredulity (noun)	incertitude (noun)
doubt about the truth of something	the state of being unsure of something