doubtfulness vs doubt

doubtfulness and doubt both are nouns.

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

As nouns, doubtfulness and doubt are synonyms defined as:

doubtfulness and doubt: uncertainty about the truth or factuality or existence of something

Other synonyms of doubtfulness include dubiousness, question.

As nouns, doubtfulness and doubt are synonyms defined as:

Other synonyms of doubtfulness include dubiety, dubiousness, incertitude, uncertainty.

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

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